JPH08256255A - Image forming device - Google Patents

Abstract

PURPOSE: To miniaturize the scale of circuits of the device as a whole by synthesizing multi-valued image data and binary image data without performing the expansion processing of image data and using a circuit for attaining a smoothing function commonly with other image data processings. CONSTITUTION: An image data synthesis part 150 is constituted of registers 151 and 153 provided with a capacity capable of holding the image data for 8 picture elements, an arithmetic part 154 and a shift register 155 for holding a processing result in the arithmetic part 154. Then, when it is judged that both binary image data which are text data and multi-valued image data which are the image data correspond to an image are specified by synthesis control data, since expression is performed only by one of the image data, the image data are also preferentially held for the bit present area of the binary image data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital type image forming apparatus for reproducing an image from dots by using binary image data or multi-valued image data, and in particular, an image is formed by mixing image data having different data lengths. The present invention relates to an improvement of an image synthesizing circuit for synthesizing and a smoothing circuit for smoothing an image.

[0002]

2. Description of the Related Art Image data for reproducing a digital image has a different data length depending on the required resolution. In recent years, various kinds of digital images have flooded offices, from binary plane images such as characters to high resolution gradation images.

An image forming apparatus for processing such a digital image is required to have a function of mixing and editing image data having different data lengths. In order to meet such a request, for example, the binary image data is expanded to the multivalued data to unify the data lengths, and then the combining process of the multivalued image data and the binary image data is executed.

On the other hand, some printers and CRT displays utilizing a dot matrix utilize a smoothing function for smoothing a step portion of an image reproduced as a set of dots to obtain a high resolution image. The circuit realizing such a smoothing function is provided with a window for fitting the image data in order to determine the characteristics of the image data.
All the image data are sequentially fitted into the window to detect the feature of the pattern of the entire image data, and the smoothing process is performed based on the detection result. A dedicated circuit is provided to speed up this smoothing operation.

[0005]

However, in the conventional synthesizing process, when synthesizing multi-valued image data and binary image data, the amount of image data is increased in order to expand the binary image data into the multi-valued image data. To increase. For example, when 8-bit multi-valued image data of 256 gradations is present in a part of the image area by this extension processing, the entire binary image data to be combined with this is extended to 8-bit multi-valued image data, so that the data amount is 8 times, and the storage capacity of the memory also becomes 8 times. That is, in the conventional combination, the entire binary image data must be expanded to the multivalued image data regardless of the multivalued image data amount, and accordingly, the memory capacity has become huge. On the other hand, if high-gradation image data is compressed into low-gradation image data, the reproducibility of the image deteriorates.

Further, since the circuit for detecting the feature of the pattern from the above-mentioned image data has a large circuit scale, various measures have been taken to reduce the circuit scale, but the effect is limited, and Since many parts such as SRAM, ROM, and gate array are required, this is a factor of increasing the product cost.

It is a first object of the present invention to provide an image forming apparatus capable of synthesizing multi-valued image data and binary image data without expanding the image data.

A second object of the present invention is to reduce the circuit scale of the apparatus as a whole by using a circuit for realizing a smoothing function also for other image data processing.

[0009]

Means for achieving the first object include first storage means for storing first image data,
An image forming apparatus provided with a second storage means for storing the second image data and a third storage means for storing a combined signal useful for combining the first image data and the second image data. The first image data, the second image data, and the combined signal are treated as a set of image data.

It is characterized in that it comprises a synthesizing means for synthesizing the first image data and the second image data by using the synthesized signal.

Another means for achieving the first object is a first storage means for storing the first image data, a second storage means for storing the second image data, and a first image data. And an image forming apparatus provided with a third storage means for storing a combined signal useful for combining the second image data,
The composite signal can combine the first image data and the second image data on a pixel-by-pixel basis.

It is characterized in that it comprises a synthesizing means for synthesizing the first image data and the second image data by using the synthesized signal.

Means for achieving the second object are window means for cutting out a part of the image data into a window of m × n dots, detecting means for detecting a feature of the image data from the image data in the window, and a detection result. A subdividing means for subdividing the dots to be output according to the above, a scaling means for enlarging or reducing the image data according to the detection result, and a selecting means for selecting the operation of the subdividing means and the scaling means. The image forming apparatus is characterized in that the subdivision means includes a smoothing circuit for reducing a step difference in an output image.

The detecting means is a memory.

Another means for achieving the second object is window means for cutting out a part of the image data into a window of m × n dots, and detecting means for detecting the characteristic of the image data from the image data in the window. Subdivision means for subdividing the dots to be output according to the detection result, scaling means for enlarging or reducing the image data according to the detection result, and selection means for selecting the operations of the subdivision means and the scaling means. It is characterized by comprising a combining means for combining the color-separated image data, and a color determining means for determining the color of the dot to be output.

The detecting means is a memory.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus of the present invention will be described by applying it to a color laser printer.

The engine portion of the color laser printer is a printing unit 6 commonly used in a plurality of embodiments described below.
00, and the schematic configuration will be described with reference to FIG.

FIG. 1 is a block diagram showing an engine portion of a color laser printer to which the present invention is applied.

The engine portion 600 mounted on the color laser printer has a charger 60 for each rotation of the image carrier 601.
2 is charged, and a color separation electrostatic latent image is formed on the image carrier 601 by image exposure by the writing device 610, and toners of a plurality of colors necessary for reproducing the electrostatic latent image in full color are individually used. And a developing device 60 by a magnetic brush developing method.
3 to 606 are selectively operated to visualize a toner image,
By repeating a series of processes for forming the toner image on the image carrier 601 a plurality of times for each color, the image carrier 601 is formed.
After the toner images of the respective colors are superposed on each other, the paper feed cassette 621
The sheets are collectively transferred by the transfer unit 607 to the transfer material sent from, and then fixed by the fixing roller 625 and discharged.

The writing device 610 includes an image data output unit 16
The semiconductor laser emits light based on the recording signal sent from 0 to form a latent image by line-scanning the image carrier 601 for each dot, which is a so-called exposure process.

The image data output section 160 is provided with a modulation circuit (not shown), an LD drive circuit (not shown), an index sensor (not shown) as a synchronization system, and an index detection circuit (not shown). A polygon driver (not shown) as a deflection optical system is provided.

The modulation circuit compares the reference wave with the analog recording signal obtained by D / A converting the recording signal consisting of a predetermined bit and multivalues it. The modulation signal thus obtained becomes the drive signal for the LD drive circuit. LD drive circuit,
A semiconductor laser 611 is oscillated by a modulation signal, and a signal corresponding to the light amount of the beam from the semiconductor laser 611 is fed back and driven so that the light amount becomes constant, and a current conducted to the semiconductor laser 611 is supplied. It can be changed. Thereby, the latent image potential can be adjusted. The synchronization system enters the index sensor (not shown) via a mirror (not shown) that reflects the beam from the deflection optical system. The index sensor outputs a current in response to the beam, and the current is converted into a current / voltage by an index detection circuit and output as an index signal. The surface position of the polygon mirror 612 that rotates at a predetermined speed is detected by this index signal, and the optical scanning is performed by the modulation signal by the raster scanning method at the cycle in the main scanning direction.

The writing device 610 oscillates the semiconductor laser 611 with a modulation signal subjected to pulse width modulation, deflects the laser light with a polygon mirror 612 rotating at a predetermined speed, and fθ
The lens 613, the first cylindrical lens (not shown), and the second cylindrical lens (not shown) focus on the image carrier 601 to scan a minute spot.

The scanning optical system constituting the writing device 610 is
A semiconductor laser 611 is provided as a coherent light source,
A collimator lens 313 is provided as a modulation optical system, and a polygon mirror 612 and an fθ lens 61 are provided as a deflection optical system.
3 is provided, and a first cylindrical lens and a second cylindrical lens are provided as a surface tilt correction optical system by the polygon mirror 612.

The semiconductor laser 611 is made of GaAlAs or the like, has a maximum output of 10 mW, a light efficiency of 25%, and a divergence angle of 8 to 16 ° in the direction parallel to the joint surface and 20 to 36 ° in the direction perpendicular to the joint surface.

Since color toners may be sequentially superposed, exposure with light having a wavelength that is less absorbed by the color toners is preferable, and the wavelength in this case is 780 nm.

The deflection optical system reduces the Pepper sum and the astigmatic difference in order to condense the beam and realize the flattening of the scanning surface.

The polygon mirror 612 is provided with eight polygon surfaces, and the writing density of 400 dpi is 16535.
4 (rpm), writing density of 600 dpi, 11023
The image carrier 6 is rotated at a rotation speed of (rpm).
01 to scan the beam.

The fθ lens 613 reduces the Pepper sum and the astigmatic difference in order to realize the flattening of the scanning surface, and removes the curvature of field.

A polygon mirror 61 is used as a correction optical system.
A first cylindrical lens (not shown) and a second cylindrical lens (not shown) are provided before and after 2 to reduce the unevenness of the scanning line pitch due to the surface tilt error of the polygon mirror 612. As a result, the polygon tilt angle is 120 seconds P
-P, and the tilt angle correction rate is 120 or more. The second cylindrical lens forms a beam on the image carrier 601.

When a recording signal is input to the image data output unit 160, the laser beam generated by the semiconductor laser 611 passes through a collimator lens and a cylindrical lens (not shown) and is rotationally scanned by a polygon mirror 612 rotated by a motor 615. After passing through the fθ lens 613 and the cylindrical lens (not shown), the optical path is bent by the mirror 614 between them, and the light is projected onto the peripheral surface of the image carrier 601 to which a uniform charge is previously given by the charger 602. Main scanning is performed to form an electrostatic latent image (hereinafter sometimes simply referred to as a latent image).

On the other hand, when the scanning is started, the laser beam is detected by an index sensor (not shown), and the first
The laser beam modulated by the color signal of the image carrier 60
The peripheral surface of 1 is scanned. Therefore, a latent image corresponding to the first color is formed on the peripheral surface of the image carrier 601 by the main scan by the laser beam and the sub-scan by the conveyance of the image carrier 601.

This latent image is subjected to reversal development by a developing device 603 loaded with yellow toner which is selectively activated, and a toner image is formed on the surface of the image carrier 601. The obtained toner image passes under the blade of a cleaning device (not shown) separated from the peripheral surface of the image carrier 601 while being held on the surface of the image carrier 601 and enters the next image forming cycle. .

That is, the image carrier 601 is charged again by the charger 602, and then the second color signal is applied to the writing controller 62.
2 is input, and writing is performed on the surface of the image carrier 601 to form a latent image in the same manner as in the case of the first color signal described above. The latent image is reversely developed by the developing device 604 loaded with magenta toner as the second color that is selectively activated.

This magenta toner image is formed in the presence of the previously formed yellow toner image.

Similarly, a developing unit 605 having a cyan toner forms a cyan toner image on the surface of the image carrier 601 in the same manner as the first and second colors.

Finally, a developing unit 606 having black toner.
Then, a black toner image is formed on the image carrier 601 in the same manner as the above-described color. These developing devices 60
DC and further AC biases are applied to the sleeves Nos. 3 to 606, and the image carrier 601 is subjected to reversal development without contact. What has been described above is the process of superposing multicolor toner images on the image carrier 601.

Thus, the multicolor toner image formed on the peripheral surface of the image carrier 601 is transferred to the transfer material sent from the paper feeding cassette 621 through the paper feeding guide to a high voltage having a polarity opposite to that of the toner at the transfer portion. Is applied and transferred.

That is, the transfer material accommodated in the paper feed cassette 621 is carried out by the rotation of the paper feed roller 622 so that one of the uppermost layers is carried out, and the image bearing member 6 is passed through the timing roller 624.
The transfer device 607 is synchronized with the leading edge of the image on 01.
Supplied with F.

The transfer material which has received the transfer of the image is separated from the rotating image carrier 601 without fail and goes upward, and the image is fixed by the fixing roller 625, and then the paper discharge roller 62.
It is discharged onto the tray 627 after passing through 6.

On the other hand, the image carrier 6 which has been transferred to the transfer material.
01 is a cleaning device (not shown) in which the blade and the toner conveying roller are kept in pressure contact with each other to remove residual toner, and after the end, the blade is separated again, and a little later than that. And the process of forming a new image is started.

The developing devices 603 to 606 contain, for example, yellow, magenta, cyan, and black developers, are equipped with a developing sleeve that keeps a predetermined gap from the image carrier 601, and the latent image on the image carrier rest 601. The image is visualized by a non-contact reversal development method. In the present embodiment, the colors of the developers are described as yellow, magenta, cyan, and black, but the present invention is not limited to this, and a color combination for reproducing a functional color that reproduces a specific color may be used. good. The configuration using the magnetic brush developing method can be applied to the one-component non-magnetic developer and the one-component magnetic developer.

FIG. 2 is a block diagram showing the image data processing circuit of the color laser printer.

The image data processing circuit 100 includes image data and character codes sent from the host computer 900, the image scanner 800 or the communication modem 700,
Print data such as an external character font and control commands are received via the external interface 130, temporarily stored in the RAM 143, converted into a character pattern by the external character font stored in the font ROM 142 or RAM 143, and then imaged on the RAM 143 by the CPU 140. Is to be expanded into image data and printed for each page.
0, the image output unit 160.

The CPU 140 is the image data processing circuit 100.
It controls the whole and operates according to a control program stored in the program ROM 141.

The image data developed into an image is printed by the printing unit 600 through the image data output unit 160, or
The image data synthesizing unit 150 synthesizes it with image data having another gradation, and then prints it by the printing unit 600 through the image data output unit 160. The image data can also be sent to another device via the external interface unit 130.

FIG. 3 is a block diagram showing a main configuration of the image data synthesizing section 150.

The image data synthesizing section 150 corresponds to the synthesizing means described in the claims, and has processing capacity in the registers 151 to 153, the computing section 154, and the computing section 154 having a capacity capable of holding image data of 8 pixels. And a shift register 155 for holding the image data. When it is determined that the image area specified by the composition control data corresponds to both binary image data that is text data and multivalued image data that is image data. Since the image data can be represented only by one of the image data, the bit data area of the binary image data is also retained with priority for the image data.

The register 151 and the register 152 hold the image data located at the same coordinates at the same time, and the register 151 corresponds to the first storage means described in the claims, and the binary image data. On the other hand, the register 152 corresponds to the second storage means described in claims, and holds, for example, 8-bit multivalued image data.

The register 153 corresponds to the third storage means in the claims and holds the synthesis control data. The synthesis control data is for selecting the image data to be output, and is for selecting which image data of the images in the overlapping areas is to be output.

The calculation unit 154 executes the processing of the logical expression shown below. The contents of this logical expression will be described below.

[0053]

[Equation 1]

OUT [7-0] is the combined image data, which is the contents of the shift register 155, and dataA
Is the logical sum of the yellow, magenta, cyan, and black components of dataT and indicates the contents of the register 151. dataI [7-0] is 8-bit multivalued image data, the contents of the register 152, and sel. Represents the content of the register 153, which is the composite control data, and each represents the pixel data of one pixel of one color.

[0055]

[Outside 1]

Next, the image synthesizing process of the color laser printer of this embodiment will be described.

FIG. 4 is a schematic diagram showing a state in which the binary image data and the multi-valued image data are combined and printed out and printed out.

The image data shown here indicates a partial area of the entire image area, and one rectangular area indicates one pixel of the image.

The image data processing unit 100 receives the image data received via the external interface 130 (see FIG. 4).
When (a) is received, it is temporarily stored in the RAM 148 and sent to the host computer 900.

The host computer 900 synthesizes the received image data (see FIG. 4A) and text data such as a document (see FIG. 4B) on the display to generate image data (see FIG. 4A). ) And text data (see FIG. 4B) are generated. The synthesis control data generated here is “E” and “F” of the text data (see FIG. 4B) representing the English characters, and “E” is converted into image data (see FIG. 4A). It is instructed to overwrite and blank out "F" from the image data.

The host computer 900 converts the above-mentioned synthesis control data into the text data shown in FIG.
The text data shown in (d) is converted into a composite control command.

The actual text data is code data showing the images shown in FIGS. 4 (c) and 4 (d).

The host computer 900 uses the text data (FIG. 4 (c) and FIG. 4) thus generated.
(See (d)) and the composite control command to the image data processing unit 100 via the external interface unit 130,
It is temporarily stored in the RAM 143. The CPU 140 converts the text data into binary image data in order to prepare for printing the image data, expands the composition control command into composition control data, and displays images of images as shown in FIGS. 4C and 4D, respectively. Convert to data. CPU140 is RAM143
The image data stored in is developed into 8-bit multivalued image data of yellow, magenta, cyan, and black. The CPU 140 sends the binary image data, the 8-bit multivalued image data, and the synthesis control data obtained as described above to the image data synthesis unit 150.

The image data synthesizing section 150 latches the binary image data, the 8-bit multi-valued image data and the synthesis control data in the register 151, the register 152 and the register 153. Each data has the same coordinates and the same number of pixels in the image area, and the number of pixels represented by each data is eight. This represents the number of pixels of image data that can be combined at the same time. Note that the number of pixels does not have to be 8, 1, 2,
The number of pixels such as 4, 8, 16, 32, etc. may be set according to the performance of the image data processing unit 100 or the printing unit 600.

Of the 8-bit composition control data latched in the register 153, for the pixel whose bit content is "O", the bit image area of the binary image data is prioritized over the multi-valued image data. FIG. 4 at 54
Since the area “E” of the binary image data shown in FIG. 4B is prioritized over the multivalued image data, the area “E” of the binary image data shown in FIG.
The multi-valued image data shown in (a) is selected with priority and latched in the shift register 155.

On the other hand, since the binary image data is unconditionally prioritized over the multi-valued image data for the pixel whose bit content is "1" in the 8-bit composite data latched in the register 151, FIG. For the “F” area of the composite control data shown in FIG. 4B), the arithmetic unit 154 selects the bitless area of the binary image data shown in FIG.

The fifth dot from the top of FIG. 4E, 3 from the left
A calculation example in the calculation unit 154 will be described taking the pixel of the dot as an example.

The text data (data at the same coordinates in FIG. 4C) of the pixel is dataT = “1”,
dataA = “1”, and the synthesis control data is shown in FIG.
The data at the same coordinates in (d), sel
It becomes "0". Therefore, the logical expression is OUT [7-0] = dataT = 1 (= 11111111b). When expressed in hexadecimal, OUT [7-0] = FFh, and the pulse width is 100%.

Image data, which is a mixture of binary image data and multi-valued image data latched in the register 155 according to the above-mentioned logical expression, is sent to the image data output section 160,
The printout is output according to the operation of the printing unit 600, and the printout is performed as shown in FIG.
The image of (e) is obtained.

The fifth dot from the top of FIG.
A calculation example will be described by taking the pixel of the dot as an example.

Text data (data at the same coordinates in FIG. 4C) of the pixel is dataT = “1”,
dataA = “1”, and the synthesis control data is shown in FIG.
The data at the same coordinates in (d), sel
It becomes "0". Therefore, the logical expression is OUT [7-0] = dataT = 1 (= 11111111b). When expressed in hexadecimal, OUT [7-0] = FFh, and the pulse width is 100%.

The fifth dot from the top of FIG. 4E, 1 from the left
A calculation example will be described by taking the pixel of the second dot as an example.

Text data (data at the same coordinates in FIG. 4C) of the pixel is dataT = “0”,
dataA = “0”, and the synthesis control data is shown in FIG.
The data at the same coordinates in (d), sel
It becomes "1". Therefore, the logical expression is OUT [7-0] = dataT = 0 (= 00000000b), and when expressed in hexadecimal, OUT [7-0] = 0h and the pulse width is 0%.

The pulse width modulation of the laser with respect to the combined image data in this embodiment is as follows.

[0075]

[Table 1]

As described above, the gradation expression by the semiconductor laser 611 is performed by changing the driving pulse width of the laser driver.
In contrast to 256 gradations of 256 to 100%, pulse widths of 0% and 10 for binary image data.
It is either 0%.

Image data in which binary image data and multi-valued image data latched in the register 155 are mixed according to the above-described logical expression is sent to the image data output section 160,
The printout is output according to the operation of the printing unit 600, and the printout is performed as shown in FIG.
The image of (e) is obtained.

Further, the CPU 140 externally connects the expanded and edited binary image data or text data, 8-bit multi-valued image data or image data, and composition control data or composition control command to the communication modem 700 or the like via the external interface 130. It is also possible to output the image data to an external device, further edit the image data with an external device, and output the image data to the external device.

In the image finally printed as described above, binary image data and 8-bit multivalued image data can be mixed in units of one pixel, but the binary image data is expanded to multivalued image data. Since it can be combined with multi-valued image data without needing a large amount of memory, it is not necessary. Further, since the binary image data can be combined with the multi-valued image data without expanding the multi-valued image data, the time spent for the expansion can be omitted and the throughput of the apparatus can be improved.

Further, when whitening out binary image data from 8-bit multi-valued image data, there is no need to perform an operation of overwriting or whitening out similar binary image data from the image data for eight planes of multi-valued image data. Becomes

The color laser printer in the above-described embodiment also requires the process of overwriting the binary image data or the process of whitening out the multivalued image data of 32 surfaces of yellow, magenta, cyan and black as in the conventional case. Therefore, the processing speed of the device does not decrease significantly. Further, since the entire binary image data is not expanded to 8-bit multi-valued image data, the memory capacity can be reduced and the cost can be reduced. Furthermore, since the process of compressing the high-gradation image data into the low-gradation image data is not performed, it is possible to prevent the image reproducibility associated with such a process.

Examples of the image forming apparatus according to claims 5 to 8 will be described below.

FIG. 5 is a block diagram showing an image data processing circuit 200 of the color laser printer, FIG. 6 is an enlarged schematic diagram of an original image, and FIG. 7 is an image data storage unit 24.
6 is a schematic diagram showing a bitmap development state of image data stored in FIG.

The image data processing circuit 200 includes a host computer 900 and an image scanner 8 as shown in FIG.
00 or data including a code including a code indicating a recording color transmitted from the communication modem 700, a data in a page description language including a color command, a character code, and the like is received through the external interface 230, and the RAM or the like is received. Of the print data, which is temporarily stored in the data storage unit 245, is converted into a character pattern by a font or an external character font, and is then converted by the CPU 240 into image data of an image on the image data storage unit 246 and printing is performed page by page. In addition, the operation unit 24
4, image data correction unit 270, image data output unit 260
Consists of

The CPU 240 is the image data processing circuit 200.
It controls the whole and operates according to a control program stored in the program ROM 241. CPU
24O performs conversion into enlarged / reduced image data according to the control code and the image data conversion table stored in the program ROM 241. The data storage unit 245 stores print data that needs to be developed into an image,
The correction pattern data and the correction image data, which are the basic data for performing the enlargement / reduction processing, are stored.

The image data storage unit 246 stores image data in a printable format. When the image data storage unit 246 performs enlargement processing or reduction processing, the image data is converted into image data enlarged / reduced by the CPU 240 and the image data is converted. To store.

Here, the image data will be described with reference to FIGS. 6 and 7.

In FIG. 6, the original image is an enlarged view of a red straight line and a green straight line, and the square size in the drawing represents the size of one pixel that can be read by the solid-state image sensor. 7A is a bitmap showing image data of a yellow component, FIG. 7B is a bitmap showing image data of a magenta component, and FIG. 7C is a bit showing image data of a cyan component. It is a map. Figure 7
The bitmaps shown in (a), FIG. 7 (b), and FIG. 7 (c) represent the same region, and the positional relationship of the coordinates in the bitmap is associated. Therefore, the yellow component and magenta component that reproduce the red straight line are at the same position on the bitmap, and the yellow component and the cyan component that reproduce the green straight line are at the same position on the bitmap.

The image data correction unit 270 applies smoothing processing to the image data and prints it out by the printing unit 600 via the image data output unit 260.

The external interface section 230 has the same function as the external interface section 130 described above, and the image data output section 260 achieves the same function as the image data output section 160 described above. Omit it.

FIG. 8 is a block diagram showing the main configuration of the image data correction unit 270, FIG. 9 is a block diagram showing the main configuration of the m × n shift register 272, and FIG. 10 is a block diagram of the shift register 274. It is a block diagram showing a configuration,
FIG. 11 is a block diagram for explaining the function of the data selector 275, FIG. 12 shows an example of a reference image pattern used for smoothing diagonal lines, and FIG. 13 shows an example of a reference image pattern for horizontal diagonal lines. It is a thing.

As shown in FIG. 8, the image data correction unit 270 includes a logic processing unit 271, a shift register 272, an image data feature detection circuit 273, a shift register 274, a data selector 275, a latch circuit 276, and a buffer circuit 2.
77, dot subdivision circuit 278, and operation selection circuit 279
Consists of

The logic processing unit 271 corresponds to the synthesizing means described in claim 8 and is a printable image data yellow as shown in FIGS. 7 (a), 7 (b) and 7 (c). The image data for each of magenta and cyan is subjected to a logical process so as to be superposed on one image data as shown in FIG.

The shift register 272 corresponds to the window means and the color determining means described in the claims. For example, as shown in FIG. 9, seven D-type flip-flops are vertically connected to form seven shift registers. A shift register of 7 × 7 bits is formed by connecting them in parallel, which constitutes a so-called window. In addition,
The number of bits is not limited to 7 × 7 bits, but is determined by the performance of the image data output unit 260 and the like.

The image data characteristic detection circuit 273 receives the logically processed image data formed in the window as an input, compares the logically processed image data with a reference image pattern having a priority order, and responds to the correction pattern. It outputs correction pattern data and bit position data.
There are a logic circuit configuration method and a memory configuration method. Since the reference image pattern includes data indicating the priority order, when the image data feature detection circuit 273 matches a plurality of reference image patterns, it is considered that only the reference image pattern having the higher priority order matches, and Ignore matches with low reference image patterns.

The reference pattern, the correction data pattern, and the bit position data will be described with reference to FIGS.

12 and 13 each show a reference image pattern having a size of 7 × 7 bits, which is the center bit or the attention bit of each reference image pattern. The "○" mark indicates that there is no bit, and the blank part is an area that does not matter whether or not there is a bit.

Further, in the figure, "A '"-"H'", "O '"-
“V ′” indicates a correction data pattern. The correction pattern data is multi-bit code data corresponding to image data. Since there are 18 kinds of correction pattern data in this embodiment, the correction pattern is included. The data has a data length of at least 5 bits. "A""in the figure ~
“H” ”,“ O ”” to “V” ”represent bit position data for determining the color of the selected captured image data, and [CENTER] selects the bit of interest. [RIGHT] selects the right neighbor of the bit of interest, [LEFT] selects the left neighbor of the bit of interest, [UPPER] selects the top neighbor of the bit of interest, and [LOWER]. ] Selects the lower neighbor of the bit of interest.

The image data feature detection circuit 273 based on the logic circuit configuration method uses the dot “present” of the reference image pattern.
Replace "none" with "1" and "0", and incorporate a logic circuit that matches the conditions of "1" and "0" in the reference image pattern.
When the same image data as the reference image pattern is input,
The correction pattern data indicating the detection result is output. The circuit according to this method can simplify the configuration, but cannot change the reference image pattern.

The image data feature detection circuit 273 based on the memory configuration method replaces the dots "present" and "absent" in the reference image pattern with "1" and "0", and uses this as the memory address to determine the address determined by the reference image pattern. By storing the correction pattern in the area, the correction pattern data of the detection result is stored in the memory at that address, and the null data is stored in the memory at other addresses, so that the same image data as the reference image pattern is stored in the memory. When input to the address line, the correction pattern data of the detection result is output from the data line. Although the circuit according to the method has a slightly complicated configuration, the reference image pattern can be changed.

As shown in FIG. 10, the shift register 274 is configured by connecting in parallel a shift register in which D flip-flops are vertically connected in four stages and a shift register in which D flip-flops are vertically connected in five stages. Image data of yellow, magenta, and cyan are generated at each of the bit position of interest and five positions above, below, left, and right thereof.

The data selector 275, for example, as shown in FIG. 11, the dot of interest and the upper and lower dots of yellow, magenta, and cyan which are expanded in the shift register 274 based on the bit position data input from the image data feature detection circuit 273. The image data of the left and right dots is selected as the corrected image data.

The latch circuit 276 and the buffer circuit 277 are for flowing the generated correction pattern data and corrected image data on the data bus.

The dot subdivision circuit 278 corresponds to the subdivision means and the smoothing means in the claims, and corrects the correction data pattern according to the color materials of yellow, magenta, cyan and black. Output to the printing unit 600.

The operation selection circuit 279 corresponds to the selection means described in the claims, and whether or not the dot subdivision circuit 278, the latch circuit 276, and the buffer circuit 277 are operated to execute the smoothing correction process. Select.

The printing section 600 outputs an image using the color materials of yellow, magenta, cyan and black as described above.

The smoothing processing operation corresponding to color reproduction in the color laser printer of this embodiment will be described below with reference to FIGS. 14 and 15.

FIG. 14 is a schematic diagram showing the logically processed image data expanded in the n × m shift register 272, and FIG. 15 is a conceptual diagram showing the subdivision processing in the dot subdivision circuit 278.

For example, when the operator commands the smoothing correction from the operation unit 244, the control signal of the CPU 240 is sent to the operation selection circuit 279. As a result, the operation selection circuit 279 brings the dot subdivision circuit 278, the latch circuit 276, and the buffer circuit 277 into the movable state in order to execute the smoothing correction process.

The image data storage unit 246 is shown in FIG.
Image data for each of yellow, magenta, and cyan as shown in FIGS. 7B and 7C is sent to the logical processing unit 271. The logical processing unit 271 performs logical processing on the image data for each of yellow, magenta, and cyan, and transfers the image data to the shift register 272 in a state of being superimposed on one image data as shown in FIG. As a result, the logically processed image data is expanded in the shift register 272 corresponding to the window.

If the shift register 272 expands the logically processed image data as shown in FIG. 14 and aligns the center of the reference pattern with the position "a '" of the reference pattern to execute the comparison process, the result shown in FIG. It is determined that the reference pattern “A” shown in FIG. Thereby, the shift register 2
Reference numeral 72 selects "A '" shown in Fig. 12 as the correction pattern corresponding to the position "a'" shown in Fig. 14, and "A""shown in Fig. 12 as the bit position data. Since the content of "A" is [RIGHT], when the bit position data is sent to the data selector 275, "A '" shown in FIG. 12 as a correction pattern for the bit of interest at the position "a'" shown in FIG. Pattern data corresponding to "" and the position "e '" shown in FIG.
The corrected image data of yellow, magenta, and cyan corresponding to the above is sent from the image data correction unit 277. in this case,
Since the image data at the position "e" shown in FIG. 6 is yellow and magenta, only magenta and yellow are sent from the data selector 275. By such processing, the correction data “Y” and “M” are associated with the portion of the position “a” shown in FIG. 6 which is not stored in the image data storage unit 246, and the color is red (color of the recording material). Then, it becomes yellow and magenta), which is shown as "A '" in FIG.

When the shift register 272 finishes comparing one bit of interest with the reference image pattern, the shift register 272 shifts the bit of interest of the logically processed image data horizontally by one bit and performs the same comparison. Take action.
When the shift register 272 completes the horizontal movement and the comparison operation for one line, the shift register 272 moves the bit of interest down by one bit and performs the same horizontal comparison operation.

In this way, the shift register 272
Sequentially performs a comparison process on all the logically processed image data to determine whether or not they apply to any of the reference image patterns, and the correction pattern data and the bit position data are selected so that all the logically processed image data are the target bits. Is processed as follows. At this time, like "a", "b" goes to "B '", "c" goes to "C'", and "d" goes to "D '".
, "E" to "E '", "f" to "F'", "g"
To "G '", "h" to "H'", "i" to "I '"
, "J" to "J '", "k" to "K'", "l"
Is converted to "L '" and "m" is converted to "M'" and transferred to the image data feature detection circuit 273.

The image data feature extraction circuit 273 is shown in FIGS. 12A to 12 for each bit of the logically processed image data.
(H) and when the attention bit of the logically processed image data expanded in the shift register 272 as compared with the reference image patterns shown in FIGS. 13 (O) to 13 (V) is aligned with the center of each reference image pattern. It is determined whether or not the logically processed image data expanded in the shift register 272 matches the reference image pattern.

Therefore, the image data feature extraction circuit 273 compares the logically processed image data developed in the shift register 272 with the reference image pattern on the basis of the bit of interest, and if the reference image pattern does not match any of the reference image patterns. A correction pattern is selected depending on whether the bit of interest is “with bit” or “without bit”, and the correction pattern data corresponding to the correction pattern is output to the latch circuit 276 and the dot subdivision circuit 278. Specifically, when the image data feature extraction circuit 273 determines that "bit exists", "X '" shown in FIG. 12 is selected and output to the latch circuit 276, and the image data feature extraction circuit 273 outputs "no bit". 14 "," Y '"is selected and output to the latch circuit 276 and the dot subdivision circuit 278 as shown in FIG.

On the other hand, the image data feature extraction circuit 273 is
As a result of comparing the logically processed image data expanded in the shift register 272 with the reference image pattern on the basis of the bit of interest, if at least one reference image pattern matches, it is determined in advance as a correction pattern for the bit of interest. 12A to 12H and 13O corresponding to the correction pattern after selecting the correction pattern.
~ "A '" ~ "H'" and "O '" shown in Fig. 13 (V)
The correction pattern data of "V '" is output to the latch circuit 276 and the dot subdivision circuit 278.

On the other hand, the image data characteristic detecting circuit 273 is selected at the same time as the correction pattern selecting process is associated with the bit position data and is sent to the data selector 275.

The data selector 275 selects yellow, magenta, and cyan image data according to the bit position data and sends the corrected image data to the dot subdivision circuit 278 in synchronization with the correction pattern data.

The dot subdividing circuit 278 indicates the normal dot pattern for the target bit in the logically processed image data based on the correction pattern data selected as described above, "X '" shown in FIG. 12 or shown in FIG. "Y '"
Is subdivided into the correction patterns of “A ′” to “H ′” shown in FIG. 12 and the correction patterns of “O ″” to “V ″” shown in FIG. 13. As a result, as shown in FIG. It acts so as to moderate the step in the direction of the vertical and diagonal lines and improve the quality of the output image. The dot subdivision circuit 278 performs pulse width modulation and sends a dot writing pulse to the image data output unit 260, and the printing unit 600 prints it out. By performing the above-described processing on all the image data, the original image as shown in FIG. 6 is subjected to smoothing correction as an image as shown in FIG.

Next, an example of the case where the smoothing process is performed on the vertical and diagonal lines by performing the enlarging / reducing process will be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 16 is a developed image showing a case in which smoothing processing is performed to double the size, and FIG. 17 is a developed image obtained by repeating twice the processing in which the smoothing process is performed and the double expansion is performed. Reference numeral 18 is a developed image showing a case where the original image is doubled without being smoothed.

The difference from the above-described smoothing processing for a simple color image is that the correction pattern data is latched in group units in the latch circuit 276, and the buffer circuit 277 is used.
Via the data storage unit 279. When the writing operation of the correction pattern data and the corrected image data to the data storage unit 279 is completed, the CPU 2
Reference numeral 40 denotes a data storage unit while referring to the image data, which is the content indicated by the index number, of the correction pattern data and the corrected image data as index numbers of the image conversion table from an image conversion table (not shown) in the program ROM 241. The correction pattern data and the corrected image data stored in 245 are converted into image data as shown in FIG. 16, and the image data is written in the image data storage unit 246. An image developed in the image data storage unit 246 in this manner is obtained as shown in FIG. Compared to the developed image shown in FIG. 18, the image is stepped or stepped and becomes somewhat smooth.
An image composed of image data obtained by repeating the above-described image conversion processing on the image data stored in the image data storage unit 246 has a step shape with gentler steps, as shown in FIG.

In the image data conversion table, the data is adjusted appropriately according to the enlargement ratio and reduction ratio of the image data.

Further, when performing the smoothing processing on the diagonal lines, the reference pattern shown in FIG. 13 in the image data feature detection circuit 73 is used as bit position information [CEN].
Either TER], [UPPER], or [LOWER] is sent to the data selector 275. As a result, the data selector 275 causes the shift register 272 to output the yellow corresponding to any one of "upper adjacent bit of the attention bit", "lower adjacent bit 1 of the attention bit", and "the attention bit itself",
The bits of magenta and cyan image data are selected and output as the color of the subdivided dots.

As described above, the smoothing correction can be performed on the color image of the vertical and horizontal diagonal lines and the horizontal and diagonal lines, and the smoothing correction can be effectively performed on the character which is an aggregate of various diagonal lines.

FIG. 19 is a block diagram showing an image data correction circuit applicable to a mono-color printer. This image data correction circuit is the image data correction circuit 20 shown in FIG.
Since the configuration in which the generation of the corrected image data is omitted from 0 is the same as the other configurations, detailed description thereof will be omitted.

[0127]

According to the inventions of claims 1 to 4, by providing the above configuration, when the multivalued image data and the binary image data are combined, the binary image data is converted into the multivalued image data. Since synthesis can be performed without expansion, an increase in storage capacity can be suppressed. Further, since it is not necessary to extend the binary image data to the multivalued image data, the processing speed of the device can be improved. Since the amount of image data is not increased as described above, the data transfer time to another image processing apparatus can be shortened.

The image forming apparatus according to any one of claims 5 to 8 is provided with the above configuration, and a signal useful for enlarging / reducing an image is generated by simply adding a small circuit to the conventional smoothing circuit. The processing work time of image enlargement / reduction can be performed at high speed, and the smoothing operation can be executed.

The image forming apparatus according to the sixth aspect can change the reference image pattern and the like by providing the above-mentioned configuration in addition to the above effects.

[Brief description of drawings]

FIG. 1 is a block diagram showing an engine portion of a color laser printer to which the present invention is applied.

FIG. 2 is a block diagram showing an image data processing circuit of a color laser printer.

3 is a block diagram showing a main configuration of an image data synthesizing unit 150. FIG.

FIG. 4 is a schematic diagram showing a state in which a binary image data and a multi-valued image data are combined and printed out to be printed out.

FIG. 5 is a block diagram showing an image data processing circuit of a color laser printer.

FIG. 6 is an enlarged schematic diagram of an original image.

FIG. 7 is a schematic diagram showing a bit map expansion state of image data stored in an image data storage unit 246.

8 is a block diagram showing a main configuration of an image data correction unit 270. FIG.

FIG. 9 is a block diagram showing a main configuration of an m × n shift register 272.

FIG. 10 is a block diagram showing a configuration of a shift register 274.

FIG. 11 is a block diagram illustrating the function of a data selector 275.

FIG. 12 shows an example of a reference image pattern used for smoothing an oblique line.

FIG. 13 shows an example of a reference image pattern for a horizontal diagonal line.

FIG. 14 is a schematic diagram showing logically processed image data expanded in an n × m shift register 272.

FIG. 15 is a conceptual diagram showing a subdivision processing in a dot subdivision circuit 278.

FIG. 16 is a developed image showing a case where smoothing processing is performed and the image is enlarged by a factor of 2;

FIG. 17 is a developed image obtained by repeating twice the process of performing the smoothing process and expanding twice.

FIG. 18 is a developed image showing a case where the original image is enlarged by a factor of 2 without performing a smoothing process.

FIG. 19 is a block diagram showing an image data correction circuit applicable to a mono-color printing device.

[Explanation of symbols]

 100 image data processing circuit 150 image data composition section 151-153 register 153 arithmetic section 154 shift register 200 image data processing circuit 245 data storage section 246 image data storage section 270 image data correction section 271 logical processing section 272 shift register 273 image data feature Detection circuit 274 Shift register 275 Data selector 276 Latch circuit 277 Buffer circuit 278 Dot subdivision circuit 279 Operation selection circuit 600 Engine part corresponding to printing part

Claims (8)

[Claims] 1. A first storage means for storing first image data, a second storage means for storing second image data, and a combination of the first image data and the second image data. In an image forming apparatus provided with a third storage means for storing a useful combined signal, an image characterized by handling the first image data, the second image data and the combined signal as a set of image data. Forming equipment. 2. The image forming apparatus according to claim 1, further comprising a synthesizing unit that synthesizes the first image data and the second image data by using a synthetic signal. 3. A first storage means for storing the first image data, a second storage means for storing the second image data, and a combination of the first image data and the second image data. In the image forming apparatus provided with a third storage means for storing a useful combined signal for the image formation, the combined signal can combine the first image data and the second image data in a pixel unit. apparatus. 4. The image forming apparatus according to claim 3, further comprising a synthesizing unit that synthesizes the first image data and the second image data by using a synthesized signal. 5. Window means for cutting out a part of the image data into a window of m × n dots, and detecting means for detecting a feature of the image data from the image data in the window.
Subdivision means for subdividing the dots to be output according to the detection result, scaling means for enlarging or reducing the image data according to the detection result, and selection means for selecting the operations of the subdivision means and the scaling means. In the image forming apparatus including the image forming apparatus, the subdividing unit includes a smoothing circuit that reduces a step in an output image. 6. The image forming apparatus according to claim 5, wherein the detection unit is a memory. 7. A window means for cutting out a part of the data into a window of m × n dots, a detecting means for detecting a feature of the image data from the image data in the window, and subdividing a dot to be output according to the detection result. Subdividing means, a scaling means for enlarging or reducing the image data according to the detection result, a selecting means for selecting operations of the subdividing means and the scaling means, and color-separated image data are combined. An image forming apparatus comprising: a synthesizing unit and a color determining unit that determines a color of a dot to be output. 8. The image forming apparatus according to claim 7, wherein the detecting unit is a memory.