JP6881118B2 - Image processing device, drive control device, light source control device, image forming device, and image processing method - Google Patents

Description

The present invention relates to an image processing device, a drive control device, a light source control device, an image forming device, and an image processing method.

In the electrophotographic process, improvement of fine line reproducibility and improvement of character reproducibility are required, and an image processing method for thinning black characters and black lines (black lines) using pattern matching is already known. ing.

However, in the conventional thinning process, when the process is executed on a figure that is in contact with each other by pattern matching, there is a problem that a gap is generated at the contact point and image deterioration occurs. As a technique for thinning black characters and black lines (black lines) using pattern matching, the amount of thinning is extracted from the image data, the thinning process is executed multiple times, and the image data is output. The process to be selected is disclosed (see Patent Document 1).

However, in the technique disclosed in Patent Document 1, since the pattern is filled so as to perform the smoothing process, for example, when the original image is plot data, the plot is not reproduced and becomes a line drawing. Therefore, when the fine line thinning process is executed on the figure that is in contact with each other at the corners, a gap is generated at the contact point, the image is deteriorated, and the problem that the reproducibility of the image data is deteriorated cannot be solved. ..

The present invention has been made in view of the above-mentioned problems, and is an image processing apparatus capable of suppressing image deterioration by detecting corner-to-corner contacts in an image and performing processing so that the contacts do not disappear. , Drive control device, light source control device, image forming device, and image processing method.

In order to solve the above-mentioned problems and achieve the object, the present invention determines whether or not the image matrix of the first resolution image data matches any one or more predetermined first patterns indicating the edge portion. The target pixel of the first resolution of the image matrix determined by the first matching unit to match the first pattern is set to a second resolution having a resolution higher than that of the first resolution. , The thinning conversion unit that performs the thinning process by replacing with the first pixel pattern associated with the first pattern, and the image matrix of the image data of the first resolution are one or more predetermined firsts indicating the contact portion. The second matching unit that determines whether or not it matches any of the two patterns and the target pixel of the image matrix determined by the second matching unit to match the second pattern are associated with the second pattern. and suppressing conversion unit performing the deterioration suppression processing to leave a contact portion between the corner and the corner by Rukoto replaced by a second pixel pattern of the second resolution that is, the determination result by the first matching unit, and the second matching A selection unit that selects and outputs the second resolution image data output from the thinning conversion unit or the second resolution image data output from the suppression conversion unit based on the determination result of the unit. It is characterized by having.

According to the present invention, image deterioration can be suppressed by detecting a contact point between corners in an image and performing a process so that the contact point does not disappear.

FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to a first embodiment. FIG. 2 is a diagram showing a configuration of an optical system of the optical scanning apparatus of the first embodiment. FIG. 3 is a diagram showing an example of an optical path from a light source to a polygon mirror. FIG. 4 is a diagram showing an example of an optical path from a light source to a polygon mirror. FIG. 5 is a diagram showing an example of an optical path from the polygon mirror to each photoconductor drum. FIG. 6 is a diagram showing an example of the configuration of the functional block of the light source control device according to the first embodiment. FIG. 7 is a diagram showing an example of the hardware configuration of the interface unit of the light source control device according to the first embodiment. FIG. 8 is a diagram showing an example of the configuration of the functional block of the image processing unit of the light source control device according to the first embodiment. FIG. 9 is a diagram showing an example of the configuration of the functional block of the drive control unit of the light source control device according to the first embodiment. FIG. 10 is a diagram showing an example of the configuration of the functional block of the modulation signal generation unit of the drive control unit of the first embodiment. FIG. 11 is a diagram showing an example of the configuration of the functional block of the image conversion unit of the modulation signal generation unit of the first embodiment. FIG. 12 is a diagram illustrating the operation of the resolution conversion process of the image conversion unit of the modulation signal generation unit of the first embodiment. FIG. 13 is a diagram showing an example of a line drawing of black pixels. FIG. 14 is a diagram showing an example of an image matrix of the first embodiment. FIG. 15 is a diagram showing an example of a pattern used in the pattern matching process before performing the thinning process on the black characters and the like of the first embodiment. FIG. 16 is a diagram showing an example of a pattern used in the pattern matching process before performing the thinning process on the black characters and the like of the first embodiment. FIG. 17 is a diagram showing an example of a pattern used in the pattern matching process before performing the thinning process on the black characters and the like of the first embodiment. FIG. 18 is a diagram showing an example of a pixel pattern of black pixels in the thinning process. FIG. 19 is a diagram illustrating an example of the operation of the thinning path of the first embodiment. FIG. 20 is a diagram illustrating an example of the operation of the thinning path of the first embodiment. FIG. 21 is a diagram illustrating an example of the operation of the thinning path of the first embodiment. FIG. 22 is a diagram illustrating an example of the operation of the thinning process for the image data of the first embodiment. FIG. 23 is a diagram showing an example of a line drawing of white pixels. FIG. 24 is a diagram showing an example of a pattern used in the pattern matching process before performing the thinning process on the white characters and the like of the first embodiment. FIG. 25 is a diagram showing an example of a pattern used in the pattern matching process before performing the thinning process on the white characters and the like of the first embodiment. FIG. 26 is a diagram illustrating an example of the operation (thickening) of the thinning path of the first embodiment. FIG. 27 is a diagram illustrating an example of the operation (thickening) of the thinning process for the image data of the first embodiment. FIG. 28 is a diagram showing an example of tag information allocation. FIG. 29 is a diagram illustrating an example of the operation of the conventional thinning process. FIG. 30 is a diagram showing a pattern used for pattern matching processing for black characters and the like of the first embodiment, and a pixel pattern of black pixels in resolution conversion processing. FIG. 31 is a diagram illustrating an example of the operation of the thinning process and the deterioration suppressing process (resolution conversion process) for the image data of the first embodiment. FIG. 32 is a diagram showing an example of the configuration of the functional block of the image conversion unit of the modulation signal generation unit of the second embodiment. FIG. 33 is a diagram showing a pattern used for the pattern matching process before the deterioration suppression process is performed on the black characters and the like of the second embodiment, and a pixel pattern of black pixels in the deterioration suppression process. FIG. 34 is a diagram illustrating an example of the operation of the thinning process and the deterioration suppressing process on the image data of the second embodiment. FIG. 35 is a diagram showing an example of the configuration of the functional block of the drive control unit of the light source control device according to the third embodiment. FIG. 36 is a diagram showing an example of the configuration of the functional block of the modulation signal generation unit of the drive control unit of the third embodiment. FIG. 37 is a diagram showing an example of the configuration of the functional block of the image conversion unit of the modulation signal generation unit of the third embodiment. FIG. 38 is a diagram showing an example of the hardware configuration of the light source drive unit of the drive control unit of the third embodiment. FIG. 39 is a diagram showing an example of the hardware configuration of the integrated light amount calculation unit of the drive control unit of the third embodiment. FIG. 40 is a diagram showing a pattern used for pattern matching processing before performing deterioration suppression processing on black characters and the like of the third embodiment, and a pixel pattern and a light amount pattern of black pixels in the deterioration suppression processing. FIG. 41 is a diagram illustrating an example of the operation of the thinning process and the deterioration suppressing process on the image data of the third embodiment. FIG. 42 is a diagram showing IL (Injection property-Light output) characteristics of the applied current of the light source and the light output (light amount). FIG. 43 is a diagram showing the relationship between the magnitudes of the applied currents when the amount of light is varied. FIG. 44 is a diagram showing a state of a line drawing when power modulation is performed by a variable amount of light. FIG. 45 is a diagram showing a pattern used for the pattern matching process before the deterioration suppression process is performed on the black characters and the like of the modified example of the third embodiment, and the pixel pattern and the light amount pattern of the black pixels in the deterioration suppression process. is there. FIG. 46 is a diagram illustrating an example of the operation of the thinning process and the deterioration suppressing process on the image data of the modified example of the third embodiment.

Hereinafter, embodiments of an image processing device, a drive control device, a light source control device, an image forming device, and an image processing method according to the present invention will be described in detail with reference to FIGS. 1 to 46. Further, the present invention is not limited by the following embodiments, and the components in the following embodiments include those easily conceived by those skilled in the art, substantially the same, and so-called equivalent ranges. Is included. Furthermore, various omissions, substitutions, changes and combinations of components can be made without departing from the gist of the following embodiments.

Further, in the following embodiments, the image forming apparatus according to the present invention is applied to a multifunction device (MFP: Multifunction Peripherals) having at least two functions of a copy function, a printer function, a scanner function, and a facsimile function. It can also be applied to an image forming apparatus such as a copying machine or a printer.

[First Embodiment]
(Rough configuration of image forming apparatus)
FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to a first embodiment. A schematic configuration of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG.

The image forming apparatus 1 shown in FIG. 1 is an apparatus for forming a printed matter by transferring toner onto a recording paper (object). The image forming apparatus 1 is a tandem type apparatus that forms a full-color image by superimposing four colors (cyan, magenta, yellow, and black).

As shown in FIG. 1, the image forming apparatus 1 includes an optical scanning apparatus 10 (forming unit), four photoconductor drums 30a, 30b, 30c, 30d, and four cleaning units 31a, 31b, 31c, 31d. It includes four charging devices 32a, 32b, 32c, 32d, four developing rollers 33a, 33b, 33c, 33d, and four toner cartridges 34a, 34b, 34c, 34d. Further, as shown in FIG. 1, the image forming apparatus 1 includes a transfer belt 40, a transfer roller 42, a density detector 45, four home position sensors 46a, 46b, 46c, 46d, and a fixing roller 50. It includes a paper feed roller 54, a registration roller pair 56, a paper discharge roller 58, a paper feed tray 60, a paper discharge tray 70, a communication control device 80, and a printer control device 90.

The photoconductor drum 30a, the cleaning unit 31a, the charging device 32a, the developing roller 33a, and the toner cartridge 34a are used as a set. These constitute an image forming station (sometimes referred to as a K station) that forms a black image.

The photoconductor drum 30b, the cleaning unit 31b, the charging device 32b, the developing roller 33b, and the toner cartridge 34b are used as a set. These constitute an image forming station (sometimes referred to as a C station) that forms an image of cyan.

The photoconductor drum 30c, the cleaning unit 31c, the charging device 32c, the developing roller 33c, and the toner cartridge 34c are used as a set. These constitute an image forming station (sometimes referred to as an M station) that forms an image of magenta.

The photoconductor drum 30d, the cleaning unit 31d, the charging device 32d, the developing roller 33d, and the toner cartridge 34d are used as a set. These constitute an image forming station (sometimes referred to as a Y station) that forms a yellow image.

The photoconductor drums 30a, 30b, 30c, and 30d may be simply referred to as "photoreceptor drum 30" when any photoconductor drum is indicated or generically used. Further, the cleaning units 31a, 31b, 31c and 31d may be simply referred to as "cleaning unit 31" when any cleaning unit is indicated or generically referred to. Further, the charging devices 32a, 32b, 32c, and 32d may be simply referred to as "charging device 32" when indicating an arbitrary charging device or generically. Further, the developing rollers 33a, 33b, 33c, and 33d may be simply referred to as "development rollers 33" when they indicate arbitrary developing rollers or when they are generically referred to. Further, the toner cartridges 34a, 34b, 34c, and 34d may be simply referred to as "toner cartridge 34" when any toner cartridge is indicated or when they are generically referred to. Further, the home position sensors 46a, 46b, 46c, and 46d may be simply referred to as "home position sensor 46" when indicating an arbitrary home position sensor or generically.

The optical scanning device 10 transmits light (laser) modulated for each color based on image data (cyan image data, magenta image data, yellow image data, black image data) to the corresponding charged photoconductor drum 30. It is an optical device that irradiates the surface of each of the above. As a result, on the surface of each photoconductor drum 30, the electric charge disappears only in the portion irradiated with light, and a latent image corresponding to the image data is formed on the surface of each photoconductor drum 30. The latent image formed on the surface of each photoconductor drum 30 moves in the direction of the corresponding developing roller 33 as the photoconductor drum 30 rotates. The details of the configuration of the optical scanning device 10 will be described later.

The photoconductor drum 30 is an example of a latent image carrier, and a photosensitive layer is formed on the surface thereof. That is, the surface of the photoconductor drum 30 is the surface to be scanned. Further, the photoconductor drums 30a, 30b, 30c, and 30d are arranged side by side so that the rotation axes are parallel to each other, and rotate in the same direction (for example, the arrow direction shown in FIG. 1).

Here, in the XYZ three-dimensional Cartesian coordinate system, the direction parallel to the central axis of each photoconductor drum 30 will be described as the Y-axis direction, and the direction along the arrangement direction of each photoconductor drum 30 will be described as the X-axis direction. ..

The cleaning unit 31 is a unit that removes toner (residual toner) remaining on the surface of the corresponding photoconductor drum 30. The surface of the photoconductor drum 30 from which the residual toner has been removed returns to a position facing the corresponding charging device 32 again.

The charging device 32 is a device that uniformly charges the surface of the corresponding photoconductor drum 30.

The developing roller 33 is a roller in which the toner from the corresponding toner cartridge 34 is thinly and uniformly applied to the surface thereof as it rotates. Then, when the toner on the surface of the developing roller 33 comes into contact with the surface of the corresponding photoconductor drum 30, it adheres to the portion of the surface irradiated with light. That is, the developing roller 33 attaches toner to the latent image formed on the surface of the corresponding photoconductor drum 30 to visualize it.

The toner cartridge 34a is a cartridge that supplies black toner to the developing roller 33a. The toner cartridge 34b is a cartridge that supplies cyan toner to the developing roller 33b. The toner cartridge 34c is a cartridge that supplies magenta toner to the developing roller 33c. The toner cartridge 34d is a cartridge that supplies yellow toner to the developing roller 33d.

The transfer belt 40 is a belt that is hung on a belt rotation mechanism and rotates in a certain direction. The outer surface of the transfer belt 40 contacts the surface of each photoconductor drum 30 at a position opposite to that of the optical scanning device 10, so that the toner images of the respective photoconductor drums 30 are sequentially superimposed on each other. It is transferred and the color toner image is transferred. Further, the outer surface of the transfer belt 40 comes into contact with the transfer roller 42.

The transfer roller 42 is a roller that comes into contact with the outer surface of the transfer belt 40 via the recording paper and transfers the color toner image formed on the transfer belt 40 to the recording paper.

The density detector 45 is arranged on the −X side of the transfer belt 40 (the position upstream of the fixing roller 50 in the traveling direction of the transfer belt 40 and downstream of the four photoconductor drums 30). This is a sensor that detects the toner density of the color toner image on the transfer belt 40.

The home position sensor 46 is a sensor that detects the home position (original position) of the rotation of the corresponding photoconductor drum 30.

The fixing roller 50 is a roller that applies heat and pressure to the recording paper to fix the toner on the recording paper. The recording paper on which the toner is fixed is sent to the paper ejection tray 70 via the paper ejection roller 58, and is sequentially stacked on the paper ejection tray 70.

The paper feed roller 54 is a member that is arranged in the vicinity of the paper feed tray 60, takes out the recording paper one by one from the paper feed tray 60, and conveys it to the resist roller pair 56.

The resist roller pair 56 is a roller pair that feeds the recording paper toward the gap between the transfer belt 40 and the transfer roller 42 at a predetermined timing. As a result, the color toner image on the transfer belt 40 is transferred to the recording paper. The recording paper transferred here is sent to the fixing roller 50.

The paper ejection roller 58 is a roller that ejects the recording paper on which the color toner image sent from the fixing roller 50 is transferred to the paper ejection tray 70.

The paper feed tray 60 is a tray for storing recording paper. The paper ejection tray 70 is a tray for stacking recording paper on which the color toner image ejected from the paper ejection roller 58 is transferred.

The communication control device 80 is a device that controls bidirectional communication with a host device 2 (for example, a computer) via a network or the like.

The printer control device 90 is a control device that comprehensively controls each device provided in the image forming device 1. The printer control device 90 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) in which a program written in a code executed by the CPU and various data used when executing the program are stored, and a working device. It has a RAM (Random Access Memory) which is a memory, an AD conversion circuit which converts analog data into digital data, and the like. Then, the printer control device 90 controls each device in response to the request from the host device 2, and sends the image data from the host device 2 to the optical scanning device 10.

(Configuration and operation of optical scanning device)
FIG. 2 is a diagram showing a configuration of an optical system of the optical scanning apparatus of the first embodiment. 3 and 4 are diagrams showing an example of an optical path from a light source to a polygon mirror. FIG. 5 is a diagram showing an example of an optical path from the polygon mirror to each photoconductor drum. The configuration and operation of the optical scanning device 10 will be described with reference to FIGS. 2 to 5.

As shown in FIG. 2, the optical scanning apparatus 10 has four light sources 200a, 200b, 200c, 200d, four coupling lenses 201a, 201b, 201c, 201d, and four aperture plates 202a, 202b as optical systems. , 202c, 202d and four cylindrical lenses 204a, 204b, 204c, 204d. Further, the optical scanning device 10 has a polygon mirror 104, four scanning lenses 105a, 105b, 105c, 105d, and six folded mirrors 106a, 106b, 106c, 106d, 108b, 108c as an optical system. .. These optical members are assembled at predetermined positions in the optical housing of the optical scanning device 10. Further, the optical scanning device 10 has a light source control device 110 as an electrical circuit, and the details of the light source control device 110 will be described later in FIGS. 6 to 11.

The light sources 200a, 200b, 200c, and 200d may be simply referred to as "light source 200" when they indicate an arbitrary light source or when they are generically referred to. Further, the coupling lenses 201a, 201b, 201c, and 201d may be simply referred to as "coupling lens 201" when any coupling lens is indicated or when they are generically referred to. Further, the opening plates 202a, 202b, 202c, and 202d may be simply referred to as "opening plate 202" when any opening plate is indicated or generically referred to. Further, the cylindrical lenses 204a, 204b, 204c, and 204d may be simply referred to as "cylindrical lens 204" when they indicate arbitrary cylindrical lenses or when they are generically referred to.

The light source 200 is a laser light source including a surface emitting laser array in which a plurality of light emitting units are two-dimensionally arranged. The plurality of light emitting parts of the surface emitting laser array are arranged so that the light emitting parts are evenly spaced when all the light emitting parts are normally projected onto a virtual line extending in the direction corresponding to the sub-scanning. The light source 200 is composed of, for example, a VCSEL (Vertical Cavity Surface Emitting Laser). The light source 200 is not limited to the VCSEL, and may be, for example, a single laser (LD: Laser Diode), an LDA (Laser Diode Array), or the like.

The coupling lens 201 is a lens that is arranged on the optical path of the luminous flux emitted from the corresponding light source 200 and that the passing luminous flux is a substantially parallel luminous flux.

The opening plate 202 is a member having an opening and shaping a luminous flux via the corresponding coupling lens 201.

The cylindrical lens 204 is a lens that forms an image of a luminous flux that has passed through the opening of the corresponding aperture plate 202 in the vicinity of the deflection reflection surface of the polygon mirror 104 in the Z-axis direction.

The optical system including the coupling lens 201a, the aperture plate 202a, and the cylindrical lens 204a is the pre-deflector optical system of the K station. The optical system including the coupling lens 201b, the aperture plate 202b, and the cylindrical lens 204b is the pre-deflector optical system of the C station. The optical system including the coupling lens 201c, the aperture plate 202c, and the cylindrical lens 204c is the pre-deflector optical system of the M station. The optical system including the coupling lens 201d, the aperture plate 202d, and the cylindrical lens 204d is the pre-deflector optical system of the Y station.

The polygon mirror 104 is an optical member having a four-sided mirror having a two-stage structure that rotates about an axis parallel to the Z axis, and each mirror functions as a deflection reflection surface. Then, in the first-stage (lower) four-sided mirror, the luminous flux from the cylindrical lens 204b and the luminous flux from the cylindrical lens 204c are deflected, respectively, and in the second-stage (upper) four-sided mirror, the luminous flux from the cylindrical lens 204a and The luminous flux from the cylindrical lens 204d is arranged so as to be deflected. Further, the respective luminous fluxes from the cylindrical lens 204a and the cylindrical lens 204b are deflected to the −X side of the polygon mirror 104, and the respective luminous fluxes from the cylindrical lens 204c and the cylindrical lens 204d are deflected to the + X side of the polygon mirror 104. ..

The scanning lens 105 causes the light spot to move in the main scanning direction on the surface of the corresponding photoconductor drum 30 with the optical power of condensing the luminous flux in the vicinity of the corresponding photoconductor drum 30 and the rotation of the polygon mirror 104. It is a lens that has optical power to move at a constant velocity.

The scanning lens 105a and the scanning lens 105b are arranged on the −X side of the polygon mirror 104. Further, the scanning lens 105a and the scanning lens 105b are laminated in the Z-axis direction. The scanning lens 105b faces the first-stage four-sided mirror. The scanning lens 105a faces the second-stage four-sided mirror.

The scanning lens 105c and the scanning lens 105d are arranged on the + X side of the polygon mirror 104. Further, the scanning lens 105c and the scanning lens 105d are laminated in the Z-axis direction. The scanning lens 105c faces the first-stage four-sided mirror. The scanning lens 105d faces the second-stage four-sided mirror.

The luminous flux that has passed through the cylindrical lens 204a and is deflected by the polygon mirror 104 passes through the scanning lens 105a, is reflected by the folded mirror 106a, and is irradiated on the photoconductor drum 30a to form a light spot. This light spot moves in the rotation axis direction of the photoconductor drum 30a as the polygon mirror 104 rotates. That is, the light spot scans on the photoconductor drum 30a. The moving direction of the light spot at this time is the "main scanning direction" of the photoconductor drum 30a, and the rotation direction of the photoconductor drum 30a is the "secondary scanning direction" of the photoconductor drum 30a.

Further, the luminous flux that has passed through the cylindrical lens 204b and is deflected by the polygon mirror 104 passes through the scanning lens 105b, is reflected by the folded mirror 106b and the folded mirror 108b, and is irradiated to the photoconductor drum 30b to generate a light spot. It is formed. This light spot moves in the rotation axis direction of the photoconductor drum 30b as the polygon mirror 104 rotates. That is, the light spot scans on the photoconductor drum 30b. The moving direction of the light spot at this time is the "main scanning direction" of the photoconductor drum 30b, and the rotation direction of the photoconductor drum 30b is the "secondary scanning direction" of the photoconductor drum 30b.

Further, the luminous flux that has passed through the cylindrical lens 204c and is deflected by the polygon mirror 104 passes through the scanning lens 105c, is reflected by the folded mirror 106c and the folded mirror 108c, respectively, and is irradiated to the photoconductor drum 30c to generate a light spot. It is formed. This light spot moves in the rotation axis direction of the photoconductor drum 30c as the polygon mirror 104 rotates. That is, the light spot scans on the photoconductor drum 30c. The moving direction of the light spot at this time is the "main scanning direction" of the photoconductor drum 30c, and the rotation direction of the photoconductor drum 30c is the "secondary scanning direction" of the photoconductor drum 30c.

Further, the luminous flux that has passed through the cylindrical lens 204d and is deflected by the polygon mirror 104 passes through the scanning lens 105d, is reflected by the folded mirror 106d, and is irradiated on the photoconductor drum 30d to form a light spot. This light spot moves in the rotation axis direction of the photoconductor drum 30d as the polygon mirror 104 rotates. That is, the light spot scans on the photoconductor drum 30d. The moving direction of the light spot at this time is the "main scanning direction" of the photoconductor drum 30d, and the rotation direction of the photoconductor drum 30d is the "secondary scanning direction" of the photoconductor drum 30d.

The folded mirrors 106a, 106b, 106c, 106d, 108b, and 108c have the optical path lengths from the polygon mirror 104 to the corresponding photoconductor drum 30 so as to coincide with each other, and the light flux in the corresponding photoconductor drum 30, respectively. Both the incident position and the incident angle are arranged so as to be equal to each other.

The optical system arranged on the optical path between the polygon mirror 104 and each of the photoconductor drums 30 is also called a scanning optical system. The optical system including the scanning lens 105a and the folding mirror 106a is the scanning optical system of the K station. The optical system including the scanning lens 105b and the two folded mirrors 106b and 108b is the scanning optical system of the C station. The optical system including the scanning lens 105c and the two folded mirrors 106c and 108c constitutes the scanning optical system of the M station. The optical system including the scanning lens 105d and the folding mirror 106d is the scanning optical system of the Y station. In each scanning optical system, the scanning lens 105 may be composed of a plurality of lenses.

(Configuration of light source control device)
FIG. 6 is a diagram showing an example of the configuration of the functional block of the light source control device according to the first embodiment. The configuration of the functional block of the light source control device 110 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 6, the light source control device 110 includes an interface unit 300 (interface unit), an image processing unit 320 (processing unit), and a drive control unit 340 (drive control device).

The interface unit 300 is a unit that acquires image data transferred from the host device 2 (for example, a computer) from the printer control device 90 and sends it to the image processing unit 320 in the subsequent stage. The specific hardware configuration of the interface unit 300 will be described later with reference to FIG.

The image processing unit 320 is, for example, a unit that performs various image processing on RGB format image data having a resolution of 1200 dpi (dots per inch) and an 8-bit number of bits. The image processing unit 320 converts the image data (for example, RGB format image data) input from the interface unit 300 into color image data (for example, CMYK format image data) corresponding to the printing method.

The drive control unit 340 receives the image data processed by the image processing unit 320, generates a modulated pulse signal corresponding to the drive of the light source 200, and drives the light source 200 by the drive signal corresponding to the modulated pulse signal. It is a unit that emits light. The drive control unit 340 is composed of, for example, a single integrated device such as an ASIC provided in the vicinity of each light source 200. Further, as shown in FIG. 6, the drive control unit 340 is connected to, for example, the image processing unit 320 by a cable 330.

<Hardware configuration of interface unit>
FIG. 7 is a diagram showing an example of the hardware configuration of the interface unit of the light source control device according to the first embodiment. The hardware configuration of the interface unit 300 of the present embodiment will be described with reference to FIG. 7.

As shown in FIG. 7, the interface unit 300 includes a CPU 400, a RAM 401, a flash memory 402, and an I / F circuit 403.

The CPU 400 is an arithmetic unit that operates according to a program stored in the flash memory 402 and controls the entire optical scanning device 10. The RAM 401 is a volatile storage device used as a work area of the CPU 400. The flash memory 402 is a non-volatile storage device that stores various programs executed by the CPU 400 and various data necessary for executing those programs. The I / F circuit 403 is a communication interface that performs bidirectional communication with the printer control device 90. For example, the I / F circuit 403 receives a printer control signal from the printer control device 90. The image data from the host device 2 is input to the light source control device 110 via the I / F circuit 403.

As shown in FIG. 7, the bus 404 is an address bus, a data bus, or the like that connects the CPU 400, the RAM 401, the flash memory 402, and the I / F circuit 403 so as to be able to communicate with each other.

<Functional block configuration of image processing unit>
FIG. 8 is a diagram showing an example of the configuration of the functional block of the image processing unit of the light source control device according to the first embodiment. The configuration of the functional block of the image processing unit 320 of the present embodiment will be described with reference to FIG.

As shown in FIG. 8, the image processing unit 320 includes an attribute separation unit 321, a color conversion unit 322, a black ink generation unit 323, a gamma correction unit 324, a tag generation unit 325, a position correction unit 326, and a floor. It is provided with a tuning processing unit 327.

The attribute separation unit 321 is a functional unit that separates the attribute information added to the image data input from the interface unit 300. The attribute information is information indicating the type of the object that is the source of the area (pixel). For example, if a pixel is a part of a character, the attribute information of that pixel indicates the attribute of the "character". If a pixel is part of a line, the pixel's attribute information indicates the "line" attribute. If a pixel is a part of a graphic, the attribute information of that pixel indicates the attribute of the "graphic". If a pixel is part of a photo, the pixel attribute information indicates the "photo" attribute.

The attribute separation unit 321 sends the separated attribute information (for example, data having the same resolution (1200 dpi) as the image data and a bit number of 2 bits) to the tag generation unit 325. Further, the attribute separation unit 321 sends the separated image data (for example, data in RGB format having 1200 dpi and 8 bits) to the color conversion unit 322.

The color conversion unit 322 is a functional unit that converts 8-bit RGB format image data into 8-bit CMY format image data that is a color reproduction color in a printer or the like. The color conversion unit 322 sends the image data converted into the CMY format to the black generation unit 323.

The black generation unit 323 is a functional unit that extracts a black component from image data converted into CMY format, determines a subsequent CMY color, and finally converts it into image data in CMYK format. The black generation unit 323 sends the image data converted into the CMYK format to the gamma correction unit 324.

The gamma correction unit 324 is a functional unit that corrects the level of each color of the image data converted into the CMYK format by linear conversion using a table or the like. The gamma correction unit 324 sends the corrected image data to the position correction unit 326.

The tag generation unit 325 is a functional unit that generates tag information indicating whether or not each pixel of 1200 dpi image data is a pixel constituting a character or a line. The tag generation unit 325 generates tag information based on the attribute information as an example. In this way, for example, by associating tag information indicating characters or a background with each pixel of image data, it is possible to perform image processing on the pixels corresponding to the tag information according to the content indicated by the tag information. It becomes. Further, the tag information may be composed of multiple bits and indicate a plurality of attributes. However, in the following, it is assumed that the tag information is composed of 1 bit, and when the tag information is "1", it means that the corresponding pixel is a character or a line, and when the tag information is "0". , The corresponding pixel will be described as indicating that it is an object other than a character or a line (for example, a background).

The tag generation unit 325 sends tag information (substantially 1200 dpi, 1-bit data) to the position correction unit 326.

The position correction unit 326 is a functional unit that receives image data from the gamma correction unit 324 and removes noise or distortion. Further, the position correction unit 326 corrects the position of the image by scaling or shifting the image. At this time, the position correction unit 326 converts the resolution of 1200 dpi to 2400 dpi. Then, the position correction unit 326 generates 2400 dpi (first resolution) CMYK format image data in which one pixel is represented by a plurality of bits (8 bits in this case) and sends the image data to the gradation processing unit 327.

The tag information generated by the tag generation unit 325 is sent to the drive control unit 340 via the position correction unit 326 and the gradation processing unit 327. Here, the position correction unit 326 applies the same processing as the process of increasing the resolution of the image data from 1200 dpi to 2400 dpi and the process of correcting the position of the image data on the tag information, and sends the tag information to the gradation processing unit 327. As a result, the position correction unit 326 can also increase the resolution of the tag information from 1200 dpi to 2400 dpi, and assign the tag information to each pixel after the resolution is increased.

The gradation processing unit 327 executes pseudo-halftone processing on the 8-bit CMYK format image data of the first resolution (2400 dpi) received from the position correction unit 326 by, for example, dither processing or error diffusion processing. This is a functional unit that generates 1-bit image data of the first resolution. Then, the gradation processing unit 327 has 1-bit image data (data related to image information) of the generated first resolution (2400 dpi) and 1 bit of the first resolution (2400 dpi) received from the position correction unit 326. Together with the tag information, for example, 2-bit image data having a first resolution (2400 dpi) in which the upper bit indicates the image information (CMYK) and the lower bit indicates the tag information is transmitted to the drive control unit 340. That is, the image data including the tag information by the gradation processing unit 327 includes 1-bit image information (black pixel, white pixel) (first pixel value) and 1-bit tag information (second pixel) in one pixel. It will be described as assuming that the image data includes 2-bit information including the pixel value). Here, the black pixel is a pixel whose pixel value related to image information is "1" when the number of gradations is reduced to 1 bit, and is a pixel in which light is emitted from the light source 200 to the photoconductor drum 30. Is. Further, the white pixel is a pixel in which the pixel value related to the image information becomes "0" when the number of gradations is reduced to 1 bit, and the light is not emitted from the light source 200 to the photoconductor drum 30. ..

Each functional unit of the image processing unit 320 shown in FIG. 8 is realized by a hardware circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

The attribute separation unit 321 of the image processing unit 320, the color conversion unit 322, the black ink generation unit 323, the gamma correction unit 324, the tag generation unit 325, the position correction unit 326, and the gradation processing unit 327 conceptually function. It is shown and is not limited to such a configuration. For example, in the image processing unit 320 shown in FIG. 8, a plurality of functional units illustrated as independent functional units may be configured as one functional unit. On the other hand, the function of one functional unit in the image processing unit 320 shown in FIG. 8 may be divided into a plurality of functions and configured as a plurality of functional units.

<Functional block configuration of drive control unit>
FIG. 9 is a diagram showing an example of the configuration of the functional block of the drive control unit of the light source control device according to the first embodiment. The configuration of the functional block of the drive control unit 340 of the present embodiment will be described with reference to FIG.

As shown in FIG. 9, the drive control unit 340 includes a modulation signal generation unit 350, a clock generation unit 360, and a light source drive unit 370.

The modulation signal generation unit 350 is a functional unit that generates a modulation pulse signal for driving the light source 200. Specifically, the modulation signal generation unit 350 generates image data having a resolution of M (2400 dpi / 2 bits in FIG. 9) (first resolution) received from the image processing unit 320 in the process of generating the modulation pulse signal. , The resolution is increased to N resolution (4800 dpi / 1 bit in FIG. 9) (second resolution) by dividing into the main scanning direction and the sub scanning direction. Further, the modulation signal generation unit 350 obtains the write start timing for each image forming station based on the output signal of the synchronization detection sensor (not shown). Then, the modulation signal generation unit 350 superimposes the dot data of the light emitting unit of the light source 200 on the clock signal from the clock generation unit 360 at the timing of the start of writing, and is based on the information from the image processing unit 320 or the like. Therefore, an independent modulated pulse signal is generated for each light emitting unit. The specific configuration of the functional block of the modulation signal generation unit 350 will be described later with reference to FIGS. 10 and 11. As described above, when the resolution of the image data is increased, the modulation signal generation unit 350 deletes the tag information included in the image data of the first resolution and is composed of pixels having a pixel value related to the image information. Although the image data of the second resolution is generated, the image data of the second resolution may still include the tag information. By leaving the tag information in the image data of the second resolution, it can be used for the subsequent processing.

The clock generation unit 360 is a functional unit that generates a clock signal indicating the timing of light emission of the light source 200. The clock signal is a signal whose image data can be modulated with a resolution corresponding to 4800 dpi (second resolution).

The light source driving unit 370 is a functional unit that outputs a driving signal of each light emitting unit of the light source 200 in response to the modulation pulse signal generated by the modulation signal generation unit 350. The light source 200 emits light with an amount of light corresponding to the drive signal of the light source drive unit 370.

The drive control unit 340 shown in FIG. 9 (furthermore, the light source control device 110 including the drive control unit 340) is configured to drive a specific light source 200, but the present invention is not limited to this, and for example, one. The drive control unit 340 (the light source control device 110 including the drive control unit 340) may drive and control four light sources 200 (light sources 200a, 200b, 200c, 200d). In the following description, the drive control unit 340 will be described as a device that controls a specific light source 200.

<Functional block configuration of the modulation signal generator>
FIG. 10 is a diagram showing an example of the configuration of the functional block of the modulation signal generation unit of the drive control unit of the first embodiment. FIG. 11 is a diagram showing an example of the configuration of the functional block of the image conversion unit of the modulation signal generation unit of the first embodiment. The configuration of the functional block of the modulation signal generation unit 350 of the drive control unit 340 of the present embodiment will be described with reference to FIGS. 10 and 11.

As shown in FIG. 10, the modulation signal generation unit 350 of the drive control unit 340 includes a buffer memory 351, an image conversion unit 352, and a gamma conversion unit 353 (pulse generation unit). The "image processing device" according to the present invention corresponds to, for example, a modulation signal generation unit 350 or an image conversion unit 352.

The buffer memory 351 is a storage unit that stores image data of 2 bits (upper bit: image information, lower bit: tag information) of the first resolution (2400 dpi) output from the image processing unit 320. The buffer memory 351 sends the accumulated image data to the image conversion unit 352 in response to reading from the image conversion unit 352 in the subsequent stage.

The image conversion unit 352 increases the resolution (resolution conversion process) from the image data of the first resolution read from the buffer memory 351 to the image data having a resolution higher than the first resolution (second resolution), and also makes the first resolution. When the target pixels are sequentially selected from the image data of the above and the target pixels are pixels that form edges (edges, contours) such as thin lines, the functional unit that performs thinning processing (thinning or thickening image processing) is there. The image conversion unit 352 sends the image data of the second resolution that has undergone image processing to the gamma conversion unit 353. Here, the image data of the second resolution is 1-bit image data composed of pixels having pixel values related to the image information. Further, the pixels constituting the edges (edges, contours) refer to pixels in the vicinity of the boundary portion between the black pixels and the white pixels. For example, the pixels constituting the edge (edge, contour) are pixels within a certain range from the boundary between the black pixel and the white pixel.

The gamma conversion unit 353 modulates the image data of the second resolution received from the image conversion unit 352 into a clock signal and converts it to a level corresponding to the characteristics of the light source 200 to obtain a modulated pulse signal which is an ON / OFF signal. It is a functional part that generates. Here, the modulated pulse signal is a serial signal, and the H period and the L period indicate the ON / OFF switching timing as they are. The gamma conversion unit 353 outputs the generated modulated pulse signal to the light source driving unit 370.

As shown in FIG. 11, the image conversion unit 352 of the modulation signal generation unit 350 includes an image matrix acquisition unit 381, a first pattern matching unit 382 (first matching unit), and a first conversion unit 383 (thinning conversion unit). ), A second pattern matching unit 384 (second matching unit), a second conversion unit 386 (an example of a suppression conversion unit), and a selector unit 387 (selection unit). Of these, the functional block in which image processing is executed by the first pattern matching unit 382 and the first conversion unit 383 is referred to as a thinning path 391, and the functional block in which image processing is executed by the second conversion unit 386 is defined as a resolution. It shall be referred to as conversion path 393.

The image matrix acquisition unit 381 is a functional unit that acquires an image matrix (for example, a 9 × 9 size partial image shown in FIG. 14 described later) for the target pixel from the image data of the first resolution stored in the buffer memory 351. Is. The pixels constituting this image matrix are 2-bit pixels including a 1-bit pixel value related to image information and a 1-bit pixel value related to tag information. That is, the image matrix is a partial image of the first resolution in a region including the target pixel and pixels around the target pixel (for example, an image in a rectangular region centered on the target pixel as shown in FIG. 14 described later). The constituent pixels are 2-bit pixels including the pixel value related to the image information and the pixel value related to the tag information. The image matrix acquisition unit 381 sends the acquired image matrix to the first pattern matching unit 382 and the second pattern matching unit 384, and sends the target pixels of the image matrix to the second conversion unit 386.

First, the resolution conversion path 393 will be described. The second conversion unit 386 of the resolution conversion path 393 sets the target pixel of the image matrix of the first resolution (for example, 2400 dpi) received from the image matrix acquisition unit 381 to the second resolution (for example) which is higher resolution than the first resolution. This is a functional unit that performs resolution conversion processing for converting to 4,800 dpi) pixels (pixels having a pixel value related to 1-bit image information). The resolution conversion path 393 sends the converted second resolution pixel to the selector unit 387. In the present embodiment, the second resolution will be described as being twice the resolution of the first resolution. The resolution conversion process will be described later with reference to FIG.

Next, the thinning path 391 will be described. In the first pattern matching unit 382 of the thinning path 391, the target pixel in the image matrix is an edge such as a thin line based on the pixel arrangement and the pixel value of the first resolution image matrix received from the image matrix acquisition unit 381. It is a functional unit that determines whether or not the pixels constitute (edges, contours). When the target pixels are sequentially selected from the image data of the first resolution by the image matrix acquisition unit 381, the arrangement of the pixels constituting the acquired image matrix is also different. Then, the first pattern matching unit 382 includes each of various patterns (for example, see FIGS. 15 to 17, 24 and 25 described later) (first pattern) stored in a buffer memory (not shown) and the acquired image. By performing pattern matching with the matrix, it is determined whether or not the target pixel included in the image matrix is a pixel constituting an edge (edge, contour) such as a thin line. Here, the size of the image matrix is determined based on the size of the pattern used for the pattern matching described above. Further, the first pattern matching unit 382 uses a matching signal indicating the result of determination by pattern matching (for example, which pattern is matched) and data of the target pixel of the image matrix that is the target of pattern matching. , Is sent to the first conversion unit 383. Further, the first pattern matching unit 382 does not output the matching signal to the first conversion unit 383 when the image matrix does not match any pattern as a result of the determination by pattern matching. Further, the first pattern matching unit 382 outputs the first enable signal to the selector unit 387 when the image matrix matches any pattern as a result of the determination by pattern matching.

The buffer memory in which the above-mentioned pattern is stored is included in, for example, a single integrated device in which the drive control unit 340 is realized, and is an integrated circuit that realizes the first pattern matching unit 382. It suffices if it is configured so that can be referred to.

Based on the matching signal received from the first pattern matching unit 382, the first conversion unit 383 of the thinning path 391 sets the target pixel (2400 dpi / 2 bits) of the image data of the first resolution into a specific pixel (2400 dpi / 2 bits) of the second resolution. This is a functional unit that converts to a pixel pattern (4800 dpi / 1 bit). That is, the first conversion unit 383 increases the resolution of the image data of the first resolution to the image data of the second resolution, and converts the target pixel into a pixel pattern to thin the black characters or black lines. Perform processing. Specifically, when the matching signal indicates that the target pixel is a pixel constituting an edge (edge, contour) such as a thin line, the first conversion unit 383 sets the target pixel of the image data of the first resolution as the target pixel. By converting to a pixel pattern (first pixel pattern) corresponding to the pattern indicated by the matching signal, thinning processing accompanied by high resolution is performed. As will be described later, by associating each pattern used for pattern matching with a pixel pattern that replaces the target pixel, it is possible to give strength or weakness to the strength of thinning. The first conversion unit 383 sends the converted second resolution pixel pattern (output data of the thinning path 391 shown in FIG. 11) to the selector unit 387.

In the second pattern matching unit 384, based on the arrangement and pixel values of the images of the first resolution image matrix received from the image matrix acquisition unit 381, the target pixels in the image matrix form the contact portion between the corners. It is a functional unit that determines whether or not the pixel is a pixel. Then, the second pattern matching unit 384 performs pattern matching between each of the various patterns (for example, see FIG. 30 (a) described later) (second pattern) stored in the buffer memory (not shown) and the acquired image matrix. By doing so, it is determined whether or not the target pixel included in the image matrix is a pixel constituting the contact portion between the corners. Further, the second pattern matching unit 384 outputs a second enable signal to the selector unit 387 when the image matrix matches any pattern as a result of determination by pattern matching.

The buffer memory in which the above-mentioned pattern is stored is included in, for example, a single integrated device in which the drive control unit 340 is realized, and is an integrated circuit that realizes the second pattern matching unit 384. It suffices if it is configured so that can be referred to.

The selector unit 387 has a second resolution pixel pattern output from the thinning path 391 (that is, output from the first conversion unit 383) and a second resolution pixel pattern output from the resolution conversion path 393 (that is, the second conversion unit 386). It is a functional unit that selects the second resolution pixel (output from) and the data to be output to the gamma conversion unit 353 from. The second resolution pixel output from the second conversion unit 386 is regarded as a pixel pattern corresponding to the pattern when the second pattern matching unit 384 determines that the image matrix matches any pattern. be able to. Specifically, the selector unit 387 selects a path for outputting data to be output to the gamma conversion unit 353 by combining the values of the first enable signal and the second enable signal shown in Table 1 below.

That is, when the second pattern matching unit 384 inputs the second enable signal, the selector unit 387 determines that the target pixel of the image matrix is a pixel constituting the contact portion between the corners, and performs resolution conversion. The second resolution pixel subjected to the image processing of the path 393 (the image processing (resolution conversion processing) here may be particularly referred to as “deterioration suppression processing”) is output. Further, when the selector unit 387 does not receive the input of the second enable signal from the second pattern matching unit 384 and receives the input of the first enable signal from the first pattern matching unit 382, the target pixel of the image matrix is an edge. It is determined that the pixels constitute (edges, contours), and a second resolution pixel pattern that has undergone image processing (thinning processing) of the thinning path 391 is output. Further, in the selector unit 387, when there is no input of the second enable signal from the second pattern matching unit 384 and no input of the first enable signal from the first pattern matching unit 382, the target pixel of the image matrix is an edge ( It is determined that the pixels do not form the pixels that make up the edges and contours, and that they are not the pixels that make up the contact points between the corners, and the image processing (resolution conversion processing) of the resolution conversion path 393 is performed for the second resolution. Output pixels.

The details of the image processing by the image conversion unit 352 will be described later in FIGS. 12 to 31.

(Image processing of image conversion unit)
The image processing of the image conversion unit 352 of the modulation signal generation unit 350 of the drive control unit 340 according to the present embodiment will be described below with reference to FIGS. 12 to 31. In addition, in FIGS. 12 to 31, the first resolution is assumed to be 2400 dpi, and the second resolution is assumed to be 4800 dpi.

<Resolution conversion process>
FIG. 12 is a diagram illustrating the operation of the resolution conversion process of the image conversion unit of the modulation signal generation unit of the first embodiment. Of the image processing of the image conversion unit 352 of the modulation signal generation unit 350, the resolution conversion processing by the second conversion unit 386 of the resolution conversion path 393 will be described with reference to FIG.

The second conversion unit 386 of the resolution conversion path 393 sets the target pixel of the first resolution image matrix received from the image matrix acquisition unit 381 as a second resolution pixel (1-bit image) having a resolution higher than the first resolution. Performs resolution conversion processing to convert to (pixels of pixel values related to information).

Specifically, as shown in FIG. 12A, the second conversion unit 386 has a pixel value of “0” related to the image information (CMYK) and is related to the tag information in the image data of the first resolution. Two pixels having a pixel value of "0" (hereinafter, may be simply referred to as "a pixel having a pixel value of (0,0)") are vertically arranged so as to have a second resolution. It is divided into two horizontally divided into a total of four pixels, and the tag information of each pixel is deleted and converted into pixels having only a pixel value "0" related to image information. Similarly, as shown in FIG. 12A, the second conversion unit 386 has a pixel value of “1” related to image information (CMYK) and pixels related to tag information in the image data of the first resolution. Pixels having a value of "1" (hereinafter, may be simply referred to as "pixels having a pixel value of (1,1)") are vertically and horizontally two so as to have a second resolution. It is divided into a total of four pixels, and the tag information of each pixel is deleted and converted into pixels having only a pixel value "1" related to image information.

Further, as shown in FIG. 12B, the second conversion unit 386 has a pixel value related to the image information (CMYK) of "0" and a pixel value related to the tag information in the image data of the first resolution. Pixels in which is "1" (hereinafter, may be simply referred to as "pixels having a pixel value of (0,1)") are arranged vertically and horizontally so as to have a second resolution. It is divided into two pixels in total of four, and the tag information of each pixel is deleted and converted into pixels having only the pixel value "0" related to the image information. Similarly, as shown in FIG. 12B, the second conversion unit 386 has a pixel value of "1" related to image information (CMYK) and pixels related to tag information in the image data of the first resolution. Pixels having a value of "0" (hereinafter, may be simply referred to as "pixels having a pixel value of (1,0)") are vertically and horizontally two so as to have a second resolution. It is divided into a total of four pixels, and the tag information of each pixel is deleted and converted into pixels having only a pixel value "1" related to image information.

As described above for the operation of the modulation signal generation unit 350, the second conversion unit 386 may include the tag information as the second resolution pixel without deleting it. Hereinafter, the second conversion unit 386 will be described as deleting the tag information.

<Thinning process>
FIG. 13 is a diagram showing an example of a line drawing of black pixels. FIG. 14 is a diagram showing an example of an image matrix of the first embodiment. 15 to 17 are diagrams showing an example of a pattern used in the pattern matching process before performing the thinning process on the black characters and the like of the first embodiment. FIG. 18 is a diagram showing an example of a pixel pattern of black pixels in the thinning process. 19 to 21 are diagrams for explaining an example of the operation of the thinning path of the first embodiment. FIG. 22 is a diagram illustrating an example of the operation of the thinning process for the image data of the first embodiment. Of the image processing of the image conversion unit 352 of the modulation signal generation unit 350, the operation of the image processing of the thinning path 391 will be mainly described with reference to FIGS. 13 to 22.

The image shown in FIG. 13 shows a part of the image data of the first resolution, and shows the edges (edges, contours) of the line drawing of the black pixels. That is, among the pixels composed of the image data shown in FIG. 13, the black pixel is a pixel having tag information indicating that it is a character or a line (pixel value (1,1)), and the white pixel is other than a character or a line. It is a pixel (pixel value (0,0)) having tag information indicating that. When the image data shown in FIG. 13 is input to the thinning path 391, the thinning process accompanied by high resolution is executed.

As described above, in the first pattern matching unit 382 of the thinning path 391, the target pixel in the image matrix is a thin line or the like based on the arrangement of the pixels of the first resolution image matrix received from the image matrix acquisition unit 381. It is determined whether or not the pixels constitute an edge (edge, contour). Specifically, the first pattern matching unit 382 acquires an image matrix (for example, a 9 × 9 size partial image shown in FIG. 14) which is a partial image centered on the target pixel from the image data of the first resolution. To do. Then, the first pattern matching unit 382 is a pattern of each of various patterns (for example, patterns A to Z and AA to AJ shown in FIGS. 15 to 17) stored in a buffer memory (not shown) and the acquired image matrix. By performing matching, it is determined whether or not the target pixel included in the image matrix is a pixel constituting an edge (edge, contour) such as a thin line. In the patterns shown in FIGS. 15 to 17, the pixel whose pixel value is indicated by "X" indicates a pixel whose pixel value does not matter. Further, the pixel of the pattern stored in the buffer memory has not only the pixel value related to the image information but also the pixel value (“0” or “1”) related to the tag information. Therefore, in the pattern matching by the first pattern matching unit 382, matching is performed between the pattern and the image matrix for both the pixel value related to the pixel information and the pixel value related to the tag information. Therefore, in pattern matching, for each of the pixels of the image matrix, the pixel value related to the pixel information and the pixel related to the tag information of the pixel corresponding to the pixel in which the pixel value related to the image information in the pattern is "0" and "1". If the values match, the image matrix is determined to match the pattern.

In addition, the first pattern matching unit 382 first uses a matching signal indicating the result of determination by pattern matching (for example, which pattern is matched) and data of the target pixel that is the target of pattern matching. It is sent to the conversion unit 383. Further, the first pattern matching unit 382 does not output the matching signal to the first conversion unit 383 when the image matrix does not match any pattern as a result of the determination by pattern matching. Further, the first pattern matching unit 382 outputs the first enable signal to the selector unit 387 when the image matrix matches any pattern as a result of the determination by pattern matching.

The first conversion unit 383 of the thinning path 391 sets the target pixel (2400 dpi / 2 bits) of the first resolution image data into the second resolution pixel pattern based on the matching signal received from the first pattern matching unit 382. It is converted to (4800 dpi / 1 bit) (for example, the pixel pattern of a to n shown in FIG. 18). That is, the first conversion unit 383 increases the resolution of the image data of the first resolution to the image data of the second resolution, and converts the target pixel into a pixel pattern to thin the black characters or black lines. Perform processing. Specifically, the first conversion unit 383 converts the target pixel of the image data of the first resolution into a pixel pattern corresponding to the pattern indicated by the matching signal, thereby performing thinning processing accompanied by high resolution.

For example, FIG. 19 shows a partial image (first resolution) in which the left side is an edge, and two pixels, the second and third pixels from the left, of the six pixels are patterned U and pattern U, respectively, by pattern matching. It is assumed that the pixels match the pattern AG. Of the two pixels matching the specific pattern, the first conversion unit 383 uses the pixel on the left side of the paper in FIG. 19 as a pixel pattern corresponding to the pattern U matching the pixel (pixel pattern h shown in FIG. 18). Replace with. Further, the first conversion unit 383 uses the pixel on the right side of the paper in FIG. 19 among the two pixels matching the specific pattern as the pixel pattern corresponding to the pattern AG matching the pixel (pixel pattern shown in FIG. 18). Replace with n).

As described above, in FIG. 19, the black pixels corresponding to two pixels are deleted (converted to white pixels) in the edge portion in the unit of the second resolution, and the line is thinned.

FIG. 20 shows a partial image (first resolution) in which the left side is an edge, and the second and third pixels from the left of the six pixels are pattern U and pattern AG, respectively, by pattern matching. It is assumed that the pixels match. Of the two pixels that match the specific pattern, the first conversion unit 383 uses the pixel on the left side of the paper in FIG. 20 as the pixel pattern corresponding to the pattern U that matches the pixel (pixel pattern a shown in FIG. 18). Replace with. Further, the first conversion unit 383 uses the pixel on the right side of the paper in FIG. 20 among the two pixels matching the specific pattern as the pixel pattern corresponding to the pattern AG matching the pixel (pixel pattern shown in FIG. 18). Replace with n).

As described above, in FIG. 20, the black pixels of 4 pixels are deleted (converted to white pixels) in the edge portion in the unit of the second resolution, and the line is thinned.

FIG. 21 shows a partial image (first resolution) in which the left side is an edge, and the second and third pixels from the left of the six pixels are pattern U and pattern AG, respectively, by pattern matching. It is assumed that the pixels match. Of the two pixels that match the specific pattern, the first conversion unit 383 uses the pixel on the left side of the paper in FIG. 21 as the pixel pattern corresponding to the pattern U that matches the pixel (pixel pattern a shown in FIG. 18). Replace with. Further, the first conversion unit 383 uses the pixel on the right side of the paper in FIG. 21 among the two pixels matching the specific pattern as the pixel pattern corresponding to the pattern AG matching the pixel (pixel pattern shown in FIG. 18). Replace with h).

As described above, in FIG. 21, the black pixels of 6 pixels are deleted (converted to white pixels) in the edge portion in the unit of the second resolution, and the line is thinned.

In addition, in FIGS. 19 to 21, since the matching signal is not output to the first conversion unit 383 for the remaining pixels that do not match the specific pattern, the resolution conversion process is performed by the second conversion unit 386 of the resolution conversion path 393. Is performed to increase the resolution to the second resolution.

FIG. 22 shows an example in which the edge portion is thinned in units of the second resolution. The image data 1000 shown in FIG. 22A is a partial image (first resolution) having an edge on the left side, and each of the pixels having the edge is replaced with a pixel pattern corresponding to the matching pattern. , As shown in FIG. 22B, the second resolution image data 1001 is generated. In the example of FIG. 22, an example of image data having an edge on the left side is shown, but by associating a pixel pattern that replaces a target pixel with each pattern used for pattern matching, the vertical direction and the horizontal direction can be changed. Therefore, it is possible to give strength to the strength of the thinning process.

FIG. 23 is a diagram showing an example of a line drawing of white pixels. 24 and 25 are diagrams showing an example of a pattern used in the pattern matching process before the thinning process is performed on the white characters and the like of the first embodiment. FIG. 26 is a diagram illustrating an example of the operation (thickening) of the thinning path of the first embodiment. FIG. 27 is a diagram illustrating an example of the operation (thickening) of the thinning process for the image data of the first embodiment. With reference to FIGS. 23 to 27, the thickening of the white line drawing (white line, white character, etc.) by the thinning process of the thinning path 391 of the image conversion unit 352 will be described.

The image shown in FIG. 23 shows a part of the image data of the first resolution, and shows the edges (edges, contours) of the line drawing of white pixels. That is, among the pixels composed of the image data shown in FIG. 23, the white pixels are pixels (pixel values (0,1)) having tag information indicating that they are characters or lines, and the black pixels are other than characters or lines. It is a pixel (pixel value (1,0)) having tag information indicating that. When the image data shown in FIG. 23 is input to the thinning path 391, the thinning process (thickening of the white line drawing) accompanied by the high resolution is executed.

As described above, in the first pattern matching unit 382 of the thinning path 391, the target pixel in the image matrix is a thin line or the like based on the arrangement of the pixels of the first resolution image matrix received from the image matrix acquisition unit 381. It is determined whether or not the pixels constitute an edge (edge, contour). Specifically, the first pattern matching unit 382 acquires an image matrix (for example, a 9 × 9 size partial image shown in FIG. 14) which is a partial image centered on the target pixel from the image data of the first resolution. To do. Then, the first pattern matching unit 382 performs pattern matching between each of the various patterns (for example, patterns BA to BX shown in FIGS. 24 and 25) stored in the buffer memory (not shown) and the acquired image matrix. It is determined whether or not the target pixel included in the image matrix is a pixel constituting an edge (edge, contour) such as a thin line of a white line drawing. In the patterns shown in FIGS. 24 and 25, the pixel whose pixel value is indicated by "X" indicates a pixel whose pixel value does not matter. Further, the pixel of the pattern stored in the buffer memory has not only the pixel value related to the image information but also the pixel value (“0” or “1”) related to the tag information. Therefore, in the pattern matching by the first pattern matching unit 382, matching is performed between the pattern and the image matrix for both the pixel value related to the pixel information and the pixel value related to the tag information. Therefore, in pattern matching, for each of the pixels of the image matrix, the pixel value related to the pixel information and the pixel related to the tag information of the pixel corresponding to the pixel in which the pixel value related to the image information in the pattern is "0" and "1". If the values match, the image matrix is determined to match the pattern.

In addition, the first pattern matching unit 382 first uses a matching signal indicating the result of determination by pattern matching (for example, which pattern is matched) and data of the target pixel that is the target of pattern matching. It is sent to the conversion unit 383. Further, the first pattern matching unit 382 does not output the matching signal to the first conversion unit 383 when the image matrix does not match any pattern as a result of the determination by pattern matching. Further, the first pattern matching unit 382 outputs the first enable signal to the selector unit 387 when the image matrix matches any pattern as a result of the determination by pattern matching.

The first conversion unit 383 of the thinning path 391 sets the target pixel (2400 dpi / 2 bits) of the first resolution image data into the second resolution pixel pattern based on the matching signal received from the first pattern matching unit 382. It is converted to (4800 dpi / 1 bit) (for example, the pixel pattern of a to n shown in FIG. 18). That is, the first conversion unit 383 increases the resolution of the image data of the first resolution to the image data of the second resolution, and converts the target pixel into a pixel pattern to substantially thicken the white character or the white line. Performs thinning processing. Specifically, the first conversion unit 383 converts the target pixel of the image data of the first resolution into a pixel pattern corresponding to the pattern indicated by the matching signal, thereby making the line thinning process (white line drawing) accompanied by high resolution. Thicken the line).

For example, FIG. 26 shows a partial image (first resolution) in which the left side is an edge of a white line drawing, and two pixels on the left side of the four pixels are converted into pattern BU and pattern BI by pattern matching, respectively. It is assumed that the pixels match. Of the two pixels matching the specific pattern, the first conversion unit 383 uses the pixel on the left side of the paper in FIG. 26 as the pixel pattern corresponding to the pattern BU matching the pixel (pixel pattern n shown in FIG. 18). Replace with. Further, the first conversion unit 383 uses the pixel on the right side of the paper in FIG. 26 as the pixel pattern corresponding to the pattern BI matching the pixel among the two pixels matching the specific pattern (pixel pattern shown in FIG. 18). Replace with f).

As described above, in FIG. 26, white pixels corresponding to two pixels are added (converted to white pixels) in the edge portion in the unit of the second resolution, and the white line drawing is thickened.

In FIG. 26, for the remaining two pixels that do not match the specific pattern, the matching signal is not output to the first conversion unit 383, so that the resolution conversion process is performed by the second conversion unit 386 of the resolution conversion path 393. It is done and the resolution is increased to the second resolution.

FIG. 27 shows an example in which the edge portion of the white line drawing is thickened (thinned) in units of the second resolution. The image data 1010 shown in FIG. 27 (a) is a partial image (first resolution) in which the right side is an edge of a white line drawing, and each pixel having the edge corresponds to a matching pattern. Is replaced with, and as shown in FIG. 27 (b), image data 1011 having a second resolution is generated. In the example of FIG. 27, an example of image data in which the right side is an edge of a white line drawing is shown, but by associating a pixel pattern that replaces a target pixel with each pattern used for pattern matching, the vertical direction and It is possible to give strength to the strength of the thinning process (strength of thickening of the white line drawing) in the left-right direction.

Further, FIG. 28 is a diagram showing an example of tag information allocation. As described above, the tag generation unit 325 generates tag information indicating whether or not each pixel of the image data of 1200 dpi is a pixel constituting a character or a line. Then, the tag information generated by the tag generation unit 325 is sent to the drive control unit 340 via the position correction unit 326 and the gradation processing unit 327. Here, the position correction unit 326 may change the tag information allocation according to the density data of the corresponding pixel (1200 dpi) and the edge direction. For example, as shown in FIG. 28, the position correction unit 326 divides the pixel density of the image data (1200 dpi) into 14 stages, divides the edge direction into four directions, and divides the pixel information (black) according to the density and phase. Pixels or white pixels) and tag information (with tag, without tag) may be changed. As a result, the image conversion unit 352 can detect a region that matches more detailed conditions from the image data of the first resolution.

<Deterioration suppression processing>
FIG. 29 is a diagram illustrating an example of the operation of the conventional thinning process. FIG. 30 is a diagram showing a pattern used for pattern matching processing for black characters and the like of the first embodiment, and a pixel pattern of black pixels in resolution conversion processing. FIG. 31 is a diagram illustrating an example of the operation of the thinning process and the deterioration suppressing process (resolution conversion process) for the image data of the first embodiment. With reference to FIGS. 29 to 31, among the image processing of the image conversion unit 352 of the modulation signal generation unit 350, the operation of the image processing operation (deterioration suppression processing) by the second pattern matching unit 384 and the resolution conversion path 393 is performed. I will explain mainly.

In the operation of the conventional thinning process shown in FIG. 29, the image data 1100 shown in FIG. 29 (a) is replaced with a pixel pattern corresponding to the matching pattern in each of the pixels constituting the edge (edge, contour). The second resolution image data 1101 as shown in FIG. 29 (b) is generated. In this case, in the image data 1100 shown in FIG. 29 (a), the portion in contact with the corner is subjected to the conventional thinning process, as in the image data 1101 shown in FIG. 29 (b). A gap is formed in the contact point, image deterioration occurs, and the reproducibility of the image data is lowered. Therefore, in the present embodiment, for example, when the image data 1100 shown in FIG. 29A is input to the second pattern matching unit 384, the following deterioration suppression processing is executed.

As described above, the second pattern matching unit 384 sets the target pixels in the image matrix to corners and corners based on the arrangement and pixel values of the images of the first resolution image matrix received from the image matrix acquisition unit 381. It is determined whether or not the pixels constitute the contact portion of the above. Specifically, the second pattern matching unit 384 acquires an image matrix (for example, a 9 × 9 size partial image shown in FIG. 14) which is a partial image centered on the target pixel from the image data of the first resolution. To do. Then, the second pattern matching unit 384 performs pattern matching between each of the various patterns (for example, the patterns CA, CB, etc. shown in FIG. 30A) stored in the buffer memory (not shown) and the acquired image matrix. Thereby, it is determined whether or not the target pixel included in the image matrix is a pixel constituting the contact portion between the corners. In the pattern shown in FIG. 30A, the pixel whose pixel value is indicated by "X" indicates a pixel whose pixel value does not matter. Further, the pixel of the pattern stored in the buffer memory has not only the pixel value related to the image information but also the pixel value (“0” or “1”) related to the tag information. Therefore, in the pattern matching by the second pattern matching unit 384, matching is performed between the pattern and the image matrix for both the pixel value related to the pixel information and the pixel value related to the tag information. Therefore, in pattern matching, for each of the pixels of the image matrix, the pixel value related to the pixel information and the pixel related to the tag information of the pixel corresponding to the pixel in which the pixel value related to the image information in the pattern is "0" and "1". If the values match, the image matrix is determined to match the pattern.

Further, the second pattern matching unit 384 outputs a second enable signal to the selector unit 387 when the image matrix matches any pattern as a result of determination by pattern matching.

When the second enable signal is input from the second pattern matching unit 384, the selector unit 387 determines that the target pixel of the image matrix is a pixel constituting the contact portion between the corners, and the resolution conversion path 393. The second resolution pixel subjected to the image processing by the second conversion unit 386 (the resolution conversion processing here may be particularly referred to as “deterioration suppression processing”) is output. Here, the output second resolution pixel means that the target pixel of the first resolution image matrix received from the image matrix acquisition unit 381 by the second conversion unit 386 of the resolution conversion path 393 is shown in FIG. 30 (b). It is converted into a second resolution pixel as shown in.

FIG. 31 shows an example in which the contact portion between corners is subjected to deterioration suppression processing in units of the second resolution. The image data 1200 shown in FIG. 31A is a partial image (first resolution) including a contact portion between corners, and each pixel of the contact portion between the corners is subjected to a second conversion unit 386. It is replaced with the converted second resolution pixel, and as shown in FIG. 31 (b), the second resolution image data 1201 is generated. As shown in the example of FIG. 31, the edge portion of the black pixel (and not the contact portion between the corners) is thinned by the thinning process by the thinning path 391, whereas it is thinned. Regarding the contact portion between the corners, the contact portion remains and no gap is generated by the deterioration suppression process by the second pattern matching unit 384 and the resolution conversion path 393.

Note that FIG. 31A shows a case where the pixels are in contact with each other at one point as the contact portion between the corners, but the purpose is not limited to this case, and for example, the upper right shown in the image data 1100. When the corners of the black pixel figure and the corners of the lower left black pixel figure are partially overlapped, the overlapped portion may also be treated as the contact portion.

As described above, in the image data, the edge portion of the black pixel (and not the contact portion between the corners) is thinned by the thinning process by the thinning path 391 to improve the reproducibility of the thin line. On the other hand, with respect to the contact portion between the corners, the contact portion remains and no gap is formed by the deterioration suppressing process by the second pattern matching unit 384 and the resolution conversion path 393. As a result, it is possible to prevent the contact from disappearing and suppress image deterioration.

[Second Embodiment]
The image forming apparatus according to the second embodiment will be described focusing on the differences from the image forming apparatus 1 according to the first embodiment. In the first embodiment, when a contact portion between corners is detected in the image data, an operation of realizing a process in which the contact is not lost by a resolution conversion process (deterioration suppression process) instead of a thinning process is performed. explained. In this embodiment, the operation of the deterioration suppression process by the deterioration suppression path will be described. The overall configuration of the image forming apparatus and the configuration of the optical scanning apparatus 10 according to the present embodiment are the same as the configurations described in the first embodiment.

(Functional block configuration of image conversion unit)
FIG. 32 is a diagram showing an example of the configuration of the functional block of the image conversion unit of the modulation signal generation unit of the second embodiment. The configuration of the functional block of the image conversion unit 352a of the modulation signal generation unit 350 of the present embodiment will be described with reference to FIG. 32.

As shown in FIG. 32, the image conversion unit 352a of the modulation signal generation unit 350 includes an image matrix acquisition unit 381, a first pattern matching unit 382 (first matching unit), and a first conversion unit 383 (thinning conversion unit). ), The second pattern matching unit 384a (second matching unit), the third conversion unit 385 (an example of the suppression conversion unit), the second conversion unit 386 (resolution conversion unit), and the selector unit 387a (selection unit). And have. Of these, the functional block in which image processing is executed by the first pattern matching unit 382 and the first conversion unit 383 is referred to as a thinning path 391, and the image processing is executed by the second pattern matching unit 384a and the third conversion unit 385. The functional block to be processed is referred to as a deterioration suppression path 392, and the functional block in which image processing is executed by the second conversion unit 386 is referred to as a resolution conversion path 393. The operation of the thinning path 391 and the resolution conversion path 393 is the same as the operation described in the first embodiment. However, the matching signal output by the first pattern matching unit 382 of the thinning path 391 will be referred to as a "first matching signal" below.

The image matrix acquisition unit 381 is a functional unit that acquires an image matrix (for example, a 9 × 9 size partial image shown in FIG. 14) for the target pixel from the image data of the first resolution stored in the buffer memory 351. .. The image matrix acquisition unit 381 sends the acquired image matrix to the first pattern matching unit 382 and the second pattern matching unit 384a, and sends the target pixels of the image matrix to the second conversion unit 386.

Next, the deterioration suppression path 392 will be described. The second pattern matching unit 384a of the deterioration suppression path 392 sets the target pixels in the image matrix to corners and corners based on the pixel arrangement and pixel values of the first resolution image matrix received from the image matrix acquisition unit 381. It is a functional unit that determines whether or not the pixels constitute the contact portion of the above. Specifically, the second pattern matching unit 384a includes each of various patterns (for example, see FIG. 33 (a) described later) (second pattern) stored in a buffer memory (not shown) and the acquired image matrix. By performing pattern matching, it is determined whether or not the target pixel included in the image matrix is a pixel forming a contact portion between corners. Further, the second pattern matching unit 384a includes a second matching signal indicating the result of determination by pattern matching (for example, which pattern matches) and a target pixel of the image matrix that is the target of pattern matching. The data is sent to the third conversion unit 385. Further, the second pattern matching unit 384a does not output the second matching signal to the third conversion unit 385 when the image matrix does not match any pattern as a result of the determination by pattern matching. Further, the second pattern matching unit 384a outputs a second enable signal to the selector unit 387a when the image matrix matches any pattern as a result of the determination by pattern matching.

The buffer memory in which the above-mentioned pattern is stored is included in, for example, a single integrated device in which the drive control unit 340 is realized, and is an integrated circuit that realizes the second pattern matching unit 384a. It suffices if it is configured so that can be referred to.

The third conversion unit 385 of the deterioration suppression path 392 sets the target pixel (2400 dpi / 2 bits) of the image data of the first resolution at the second resolution based on the second matching signal received from the second pattern matching unit 384a. This is a functional unit that converts to a specific pixel pattern (4800 dpi / 1 bit). That is, the third conversion unit 385 increases the resolution of the image data of the first resolution to the image data of the second resolution and converts the target pixel into a pixel pattern to leave the contact portion between the corners. Deterioration suppression processing is performed. Specifically, when the second matching signal indicates that the target pixel is a pixel constituting the contact portion between the corners, the third conversion unit 385 selects the target pixel of the image data of the first resolution. By converting to a pixel pattern (second pixel pattern) corresponding to the pattern indicated by the second matching signal, deterioration suppression processing accompanied by higher resolution is performed. As will be described later, by associating each pattern used for pattern matching with a pixel pattern that replaces the target pixel, it is possible to give strength to the strength of deterioration suppression. The third conversion unit 385 sends the converted second resolution pixel pattern (output data of the deterioration suppression path 392 shown in FIG. 32) to the selector unit 387a.

The selector unit 387a has a second resolution pixel pattern output from the thinning path 391 (that is, output from the first conversion unit 383) and a deterioration suppression path 392 (that is, output from the third conversion unit 385). Data output from the second resolution pixel pattern (output from) and the second resolution pixel output from the resolution conversion path 393 (that is, output from the second conversion unit 386) to the gamma conversion unit 353. It is a functional part to select. Specifically, the selector unit 387a selects a path for outputting data to be output to the gamma conversion unit 353 by combining the values of the first enable signal and the second enable signal shown in Table 2 below.

That is, when the second enable signal is input from the second pattern matching unit 384a, the selector unit 387a determines that the target pixel of the image matrix is a pixel constituting the contact portion between the corners and suppresses deterioration. A second resolution pixel pattern that has undergone image processing (deterioration suppression processing) of path 392 is output. Further, when the selector unit 387a does not receive the input of the second enable signal from the second pattern matching unit 384a and receives the input of the first enable signal from the first pattern matching unit 382, the target pixel of the image matrix is an edge. It is determined that the pixels constitute (edges, contours), and a second resolution pixel pattern that has undergone image processing (thinning processing) of the thinning path 391 is output. Further, in the selector unit 387a, when there is no input of the second enable signal from the second pattern matching unit 384a and no input of the first enable signal from the first pattern matching unit 382, the target pixel of the image matrix is an edge ( It is determined that the pixels do not form the pixels that make up the edges and contours, and that they are not the pixels that make up the contact points between the corners, and the image processing (resolution conversion processing) of the resolution conversion path 393 is performed for the second resolution. Output pixels.

(Deterioration suppression processing)
FIG. 33 is a diagram showing a pattern used for the pattern matching process before the deterioration suppression process is performed on the black characters and the like of the second embodiment, and a pixel pattern of black pixels in the deterioration suppression process. FIG. 34 is a diagram illustrating an example of the operation of the thinning process and the deterioration suppressing process on the image data of the second embodiment. Of the image processing of the image conversion unit 352a of the modulation signal generation unit 350, the operation of the image processing of the deterioration suppression path 392 will be mainly described with reference to FIGS. 33 and 34.

As described above, the second pattern matching unit 384a of the deterioration suppression path 392 sets the target pixels in the image matrix based on the pixel arrangement and pixel values of the first resolution image matrix received from the image matrix acquisition unit 381. , It is determined whether or not the pixel constitutes the contact portion between the corners. Specifically, the second pattern matching unit 384a is a pattern of each of various patterns (for example, patterns CA, CB, etc. shown in FIG. 33 (a)) stored in a buffer memory (not shown) and the acquired image matrix. By performing matching, it is determined whether or not the target pixel included in the image matrix is a pixel constituting a contact portion between corners. Further, the pixel of the pattern stored in the buffer memory has not only the pixel value related to the image information but also the pixel value (“0” or “1”) related to the tag information. Therefore, in the pattern matching by the second pattern matching unit 384a, matching is performed between the pattern and the image matrix for both the pixel value related to the pixel information and the pixel value related to the tag information. Therefore, in pattern matching, for each of the pixels of the image matrix, the pixel value related to the pixel information and the pixel related to the tag information of the pixel corresponding to the pixel in which the pixel value related to the image information in the pattern is "0" and "1". If the values match, the image matrix is determined to match the pattern.

Further, the second pattern matching unit 384a includes a second matching signal indicating the result of determination by pattern matching (for example, which pattern matches) and a target pixel of the image matrix that is the target of pattern matching. The data is sent to the third conversion unit 385. Further, the second pattern matching unit 384a does not output the second matching signal to the third conversion unit 385 when the image matrix does not match any pattern as a result of the determination by pattern matching. Further, the second pattern matching unit 384a outputs a second enable signal to the selector unit 387a when the image matrix matches any pattern as a result of the determination by pattern matching.

The third conversion unit 385 of the deterioration suppression path 392 sets the target pixel (2400 dpi / 2 bits) of the image data of the first resolution at the second resolution based on the second matching signal received from the second pattern matching unit 384a. Converts to a specific pixel pattern (4800 dpi / 1 bit). That is, the third conversion unit 385 increases the resolution of the image data of the first resolution to the image data of the second resolution and converts the target pixel into a pixel pattern to leave the contact portion between the corners. Deterioration suppression processing is performed. Specifically, the third conversion unit 385 converts the target pixel of the image data of the first resolution into a pixel pattern corresponding to the pattern indicated by the second matching signal, thereby performing deterioration suppression processing accompanied by higher resolution. Do.

When the second pattern matching unit 384a inputs the second enable signal, the selector unit 387a determines that the target pixel of the image matrix is a pixel constituting the contact portion between the corners, and the deterioration suppression path 392. Outputs a second resolution pixel pattern that has undergone image processing (deterioration suppression processing). Here, the output second resolution pixel pattern means that the target pixel of the first resolution image matrix received from the image matrix acquisition unit 381 by the third conversion unit 385 of the deterioration suppression path 392 is shown in FIG. 33 (b). ) Is converted into a second resolution pixel pattern.

FIG. 34 shows an example in which the contact portion between the corners is subjected to deterioration suppression processing in units of the second resolution. The image data 1210 shown in FIG. 34A is a partial image (first resolution) including the contact portion between the corners, and each pixel of the contact portion between the corners is subjected to the third conversion unit 385. It is replaced with the converted second resolution pixel pattern, and as shown in FIG. 34 (b), the second resolution image data 1211 is generated. As shown in the example of FIG. 34, the edge portion of the black pixel (and not the contact portion between the corners) is thinned by the thinning process by the thinning path 391. The contact portion between the corners is prevented from forming a gap because the contact portion remains by the deterioration suppression process according to the deterioration suppression path 392.

As described above, in the image data, the edge portion of the black pixel (and not the contact portion between the corners) is thinned by the thinning process by the thinning path 391 to improve the reproducibility of the thin line. On the other hand, the contact portion between the corners is prevented from forming a gap by leaving the contact portion by the deterioration suppression treatment by the deterioration suppression path 392. As a result, it is possible to prevent the contact from disappearing and suppress image deterioration.

[Third Embodiment]
The image forming apparatus according to the third embodiment will be described focusing on the differences from the image forming apparatus according to the second embodiment. In the second embodiment, when the contact portion between the corners is detected in the image data, the operation of performing deterioration suppression processing for leaving the contact portion between the corners by converting the target pixel into a pixel pattern is performed. explained. In this embodiment, an operation of converting a target pixel into a pixel pattern by a deterioration suppressing process and changing the amount of light of a specific pixel of the pixel pattern will be described. The overall configuration of the image forming apparatus and the configuration of the optical scanning apparatus 10 according to the present embodiment are the same as the configurations described in the first embodiment.

(Functional block configuration of drive control unit)
FIG. 35 is a diagram showing an example of the configuration of the functional block of the drive control unit of the light source control device according to the third embodiment. The configuration of the functional block of the drive control unit 340b of the present embodiment will be described with reference to FIG. 35.

As shown in FIG. 35, the drive control unit 340b includes a modulation signal generation unit 350b, a clock generation unit 360, a light source drive unit 370b, a scaling value holding unit 371, a power modulation current setting unit 372, and a normal current. It includes a setting unit 373, a threshold current setting unit 374, a second selector unit 375, and an integrated light amount calculation unit 376. Further, the optical scanning device 10 includes a photodetector 250 that receives light output from the light source 200 in the vicinity of the light source 200.

The modulation signal generation unit 350b is a functional unit that generates a light source modulation pulse signal and a power modulation control pulse signal for driving the light source 200. Specifically, the modulation signal generation unit 350b is the image data having the resolution of M (2400 dpi / 2 bits in FIG. 35) (first resolution) received from the image processing unit 320 in the process of generating the light source modulation pulse signal. Is divided into a main scanning direction and a sub-scanning direction to increase the resolution to N resolution (4800 dpi / 1 bit in FIG. 35) (second resolution). Further, the modulation signal generation unit 350b obtains the write start timing for each image forming station based on the output signal of the synchronization detection sensor (not shown). Then, the modulation signal generation unit 350b superimposes the dot data of the light emitting unit of the light source 200 on the clock signal from the clock generation unit 360 at the timing of the start of writing, and is based on the information from the image processing unit 320 or the like. Therefore, an independent light source modulation pulse signal and power modulation control pulse signal are generated for each light emitting unit. The specific configuration of the functional block of the modulated signal generation unit 350b will be described later with reference to FIGS. 36 and 37. As described above, the modulation signal generation unit 350b is composed of pixels having pixel values related to the image information by deleting the tag information included in the image data of the first resolution when the image data is increased in resolution. Although the image data of the second resolution is generated, the image data of the second resolution may still include the tag information.

The clock generation unit 360 is a functional unit that generates a clock signal indicating the timing of light emission of the light source 200. The clock signal is a signal whose image data can be modulated with a resolution corresponding to 4800 dpi (second resolution).

The light source drive unit 370b is a functional unit that outputs a drive signal (applied current) of each light emitting unit of the light source 200 in response to a light source modulation pulse signal or the like generated by the modulation signal generation unit 350b. The light source 200 emits light with an amount of light corresponding to the drive signal of the light source drive unit 370b. The specific hardware configuration of the light source driving unit 370b will be described later with reference to FIG. 38.

The variable magnification value holding unit 371 is a functional unit that holds a variable magnification value that defines how many times the amount of light for power modulation is multiplied by the normal amount of light. The variable value holding unit 371 may hold the variable value in the register as a set value, or may hold the variable value in the lookup table.

The power modulation current setting unit 372 calculates the power modulation current setting value from the normal current setting value output from the normal current setting unit 373 and the power modulation variable magnification value held by the variable magnification value holding unit 371. It is a functional part to do. The power modulation current setting unit 372 outputs the calculated power modulation current setting value to the second selector unit 375.

The normal current setting unit 373 is a functional unit that calculates a normal current setting value for setting the light amount of light output from the light source 200 as a target light amount from the light amount feedback value output from the integrated light amount calculation unit 376. The normal current setting unit 373 outputs the calculated normal current setting value to the second selector unit 375.

The threshold current setting unit 374 is a functional unit that derives a threshold current setting value for applying the threshold current described later in FIG. 42 to the light source 200 based on information from the outside. The threshold current setting unit 374 outputs the derived threshold current setting value to the light source drive unit 370b.

The second selector unit 375 has a normal current set value input from the normal current setting unit 373 and a power modulation current input from the power modulation current setting unit 372 according to the power modulation control pulse signal output from the modulation signal generation unit 350b. It is a function unit that switches the output with any of the set values as the exposure current set value. The second selector unit 375 outputs the exposure current set value to be switched and output to the light source driving unit 370b.

The integrated light amount calculation unit 376 is a functional unit that converts the light amount of the output light from the light source 200 detected by the photodetector 250 into a voltage value and outputs the voltage value as a light amount feedback value to the normal current setting unit 373. Is.

The drive control unit 340b shown in FIG. 35 (furthermore, the light source control device 110 including the drive control unit 340b) is configured to drive a specific light source 200, but the present invention is not limited to this, and for example, one. The drive control unit 340b (the light source control device 110 including the drive control unit 340b) may drive and control four light sources 200 (light sources 200a, 200b, 200c, 200d). In the following description, the drive control unit 340b will be described as a device that controls a specific light source 200.

(Functional block configuration of the modulated signal generator)
FIG. 36 is a diagram showing an example of the configuration of the functional block of the modulation signal generation unit of the drive control unit of the third embodiment. FIG. 37 is a diagram showing an example of the configuration of the functional block of the image conversion unit of the modulation signal generation unit of the third embodiment. The configuration of the functional block of the modulation signal generation unit 350b of the drive control unit 340b of the present embodiment will be described with reference to FIGS. 36 and 37.

As shown in FIG. 36, the modulation signal generation unit 350b of the drive control unit 340b includes a buffer memory 351, an image conversion unit 352b, and a gamma conversion unit 353b. The "image processing device" according to the present invention corresponds to, for example, a modulation signal generation unit 350b or an image conversion unit 352b.

The buffer memory 351 is a storage unit that stores image data of 2 bits (upper bit: image information, lower bit: tag information) of the first resolution (2400 dpi) output from the image processing unit 320. The buffer memory 351 sends the accumulated image data to the image conversion unit 352b in response to reading from the image conversion unit 352b in the subsequent stage.

The image conversion unit 352b increases the resolution (resolution conversion processing) from the image data of the first resolution read from the buffer memory 351 to the image data having a resolution higher than the first resolution (second resolution), and also makes the first resolution. When the target pixels are sequentially selected from the image data of the above and the target pixels are pixels that form edges (edges, contours) such as thin lines, the functional unit that performs thinning processing (thinning or thickening image processing) is there. Further, the image conversion unit 352b sequentially selects a target pixel from the image data of the first resolution, and when the target pixel is a pixel constituting a contact portion between the corners, the deterioration suppressing process is performed. The image conversion unit 352b sends the image data (pixels or pixel patterns) and the light amount data (described later in FIG. 37) of the second resolution that has undergone image processing to the gamma conversion unit 353b. Here, the image data of the second resolution is 1-bit image data composed of pixels having pixel values related to the image information.

The gamma conversion unit 353b is an ON / OFF signal by modulating the second resolution image data and the light amount data received from the image conversion unit 352b into a clock signal and converting it to a level corresponding to the characteristics of the light source 200. It is a functional unit that generates a light source modulation pulse signal and a power modulation control pulse signal. Here, the light source modulation pulse signal and the power modulation control pulse signal are serial signals, and the H period and the L period indicate the ON / OFF switching timing as they are. The gamma conversion unit 353b outputs the generated light source modulation pulse signal to the light source drive unit 370b, and outputs the generated power modulation control pulse signal to the second selector unit 375.

As shown in FIG. 37, the image conversion unit 352b of the modulation signal generation unit 350b includes an image matrix acquisition unit 381, a first pattern matching unit 382 (first matching unit), and a first conversion unit 383 (thinning conversion unit). ), The second pattern matching unit 384b (second matching unit), the third conversion unit 385b (an example of the suppression conversion unit), the second conversion unit 386 (resolution conversion unit), and the first selector unit 387b (selection). Part) and. Of these, the functional block in which the image processing is executed by the first pattern matching unit 382 and the first conversion unit 383 is referred to as a thinning path 391, and the image processing is executed by the second pattern matching unit 384b and the third conversion unit 385b. The functional block to be processed is referred to as a deterioration suppression path 392b, and the functional block in which image processing is executed by the second conversion unit 386 is referred to as a resolution conversion path 393. The operation of the thinning path 391 and the resolution conversion path 393 is the same as the operation described in the second embodiment.

The image matrix acquisition unit 381 is a functional unit that acquires an image matrix (for example, a 9 × 9 size partial image shown in FIG. 14) for the target pixel from the image data of the first resolution stored in the buffer memory 351. .. The image matrix acquisition unit 381 sends the acquired image matrix to the first pattern matching unit 382 and the second pattern matching unit 384b, and sends the target pixels of the image matrix to the second conversion unit 386.

Next, the deterioration suppression path 392b will be described. The second pattern matching unit 384b of the deterioration suppression path 392b sets the target pixels in the image matrix to corners and corners based on the pixel arrangement and pixel values of the first resolution image matrix received from the image matrix acquisition unit 381. It is a functional unit that determines whether or not the pixels constitute the contact portion of the above. Specifically, the second pattern matching unit 384b includes each of various patterns (for example, see FIG. 40 (a) described later) (second pattern) stored in a buffer memory (not shown) and the acquired image matrix. By performing pattern matching, it is determined whether or not the target pixel included in the image matrix is a pixel forming a contact portion between corners. Further, the second pattern matching unit 384b includes a second matching signal indicating the result of determination by pattern matching (for example, which pattern matches) and a target pixel of the image matrix that is the target of pattern matching. The data is sent to the third conversion unit 385b. Further, the second pattern matching unit 384b does not output the second matching signal to the third conversion unit 385b when the image matrix does not match any pattern as a result of the determination by pattern matching. Further, the second pattern matching unit 384b outputs a second enable signal to the first selector unit 387b when the image matrix matches any pattern as a result of determination by pattern matching.

The buffer memory in which the above-mentioned pattern is stored is included in, for example, a single integrated device in which the drive control unit 340b is realized, and is an integrated circuit that realizes the second pattern matching unit 384b. It suffices if it is configured so that can be referred to.

The third conversion unit 385b of the deterioration suppression path 392b sets the target pixel (2400 dpi / 2 bits) of the image data of the first resolution at the second resolution based on the second matching signal received from the second pattern matching unit 384b. It is a functional unit that converts a specific pixel pattern (4800 dpi / 1 bit) and light amount data that defines which pixel of the pixel pattern the light amount is to be strengthened (high exposure). That is, the third conversion unit 385b increases the resolution of the image data of the first resolution to the image data of the second resolution and converts the target pixel into the pixel pattern and the amount of light data, so that the contact portion between the corners. Is left, and deterioration suppression processing is performed to generate light amount data for strengthening the light amount of the pixel related to the remaining contact portion. Specifically, when the second matching signal indicates that the target pixel is a pixel constituting the contact portion between the corners, the third conversion unit 385b selects the target pixel of the image data of the first resolution. Deterioration suppression processing accompanied by higher resolution is performed by converting into pixel patterns and light amount data corresponding to the pattern indicated by the second matching signal. As will be described later, by associating the pixel pattern that replaces the target pixel and the light intensity data with each of the patterns used for pattern matching in this way, it is possible to give strength to the strength of deterioration suppression. The third conversion unit 385b sends the converted second resolution pixel pattern (output data of the deterioration suppression path 392b shown in FIG. 37) to the first selector unit 387b.

The first selector unit 387b is output from the second resolution pixel pattern output from the thinning path 391 (that is, output from the first conversion unit 383) and the deterioration suppression path 392b (that is, the third conversion). The gamma conversion unit from the second resolution pixel pattern and light amount data (output from unit 385b) and the second resolution pixel output from the resolution conversion path 393 (that is, output from the second conversion unit 386). This is a functional unit that selects data to be output to 353b. Specifically, the first selector unit 387b selects a path for outputting data to be output to the gamma conversion unit 353b by combining the values of the first enable signal and the second enable signal shown in Table 2 above.

That is, when the first selector unit 387b receives the input of the second enable signal from the second pattern matching unit 384b, the first selector unit 387b determines that the target pixel of the image matrix is a pixel constituting the contact portion between the corners. The second resolution pixel pattern and the light amount data obtained by performing the image processing (deterioration suppression processing) of the deterioration suppression path 392b are output. Further, in the first selector unit 387b, when there is no input of the second enable signal from the second pattern matching unit 384b and there is an input of the first enable signal from the first pattern matching unit 382, the target pixel of the image matrix is , It is determined that the pixels constitute edges (edges, contours), and a second resolution pixel pattern that has undergone image processing (thinning processing) of the thinning path 391 is output. Further, when the first selector unit 387b has no input of the second enable signal from the second pattern matching unit 384b and no input of the first enable signal from the first pattern matching unit 382, the target pixel of the image matrix is A second image processing (resolution conversion processing) of the resolution conversion path 393 was performed, judging that it is not a pixel that constitutes an edge (edge, contour) and is not a pixel that constitutes a contact portion between corners. Output resolution pixels.

(Hardware configuration of light source drive unit)
FIG. 38 is a diagram showing an example of the hardware configuration of the light source drive unit of the drive control unit of the third embodiment. The hardware configuration of the light source drive unit 370b of the drive control unit 340b of the present embodiment will be described with reference to FIG. 38.

As shown in FIG. 38, the light source drive unit 370b of the drive control unit 340b includes a DAC (Digital to Analog Converter) 377a, 377b, a current source 378a, 378b, and a switch 379a, 379b. The light source 200 shown in FIG. 38 will be described as having a single laser LD as a light emitting unit.

The DAC 377a is an electronic component that converts an exposure current set value, which is digital data output from the second selector unit 375, into an analog signal. The DAC 377b is an electronic component that converts a threshold current setting value, which is digital data output from the threshold current setting unit 374, into an analog signal.

The current source 378a is a device that adjusts the current flowing through the single laser LD of the light source 200 so as to be the current indicated by the exposure current set value, based on the analog signal of the exposure current set value output from the DAC 377a. That is, by controlling the exposure current set value, it is possible to control how much light the light source 200 emits. For example, if you want to make the single laser LD emit light with a normal amount of light, you can set the exposure current set value to the normal current set value, and if you want to make the single laser LD emit light with strong exposure, power-modulate the exposure current set value. It may be the current set value.

The current source 378b is a device that adjusts the current flowing through the single laser LD of the light source 200 so as to be the current indicated by the threshold current set value, based on the analog signal of the threshold current set value output from the DAC 377b.

The switch 379a is an electronic component that opens and closes a circuit from the current source 378a to the single laser LD based on the light source modulation pulse signal output from the modulation signal generation unit 350b. The switch 379b is an electronic component that opens and closes a circuit from the current source 378b to the single laser LD based on the light source modulation pulse signal output from the modulation signal generation unit 350b. When the switches 379a and 379b are in the open state, a current flows in the forward direction from the power supply Vcc toward the switches 379a and 379b to the single laser LD of the light source 200, and the single laser LD emits light. The opening / closing operation based on the light source modulation pulse signal by the switches 379a and 379b enables light emission control of the light source 200 with respect to the single laser LD in a desired lighting pattern.

(Hardware configuration of integrated light amount calculation unit)
FIG. 39 is a diagram showing an example of the hardware configuration of the integrated light amount calculation unit of the drive control unit of the third embodiment. The hardware configuration of the integrated light amount calculation unit 376 of the drive control unit 340b of the present embodiment will be described with reference to FIG. 39.

As shown in FIG. 39, the integrated light amount calculation unit 376 of the drive control unit 340b includes an LPF (Low-Pass Filter) 376a and an ADC (Analog to Digital Converter) 376b. The photodetector 250 shown in FIG. 39 will be described as having a photodiode PD as a detection unit.

The photodiode PD is a diode that generates and outputs a voltage (detection voltage) corresponding to the amount of light of the output light when the output light from the light source 200 is detected.

LPF376a is an electronic circuit that averages the detected voltage from the photodiode PD. The ADC 376b is an electronic component that converts the detection voltage averaged by the LPF376a into a digital signal and outputs it as a light amount feedback value.

(Deterioration suppression processing)
FIG. 40 is a diagram showing a pattern used for pattern matching processing before performing deterioration suppression processing on black characters and the like of the third embodiment, and a pixel pattern and a light amount pattern of black pixels in the deterioration suppression processing. FIG. 41 is a diagram illustrating an example of the operation of the thinning process and the deterioration suppressing process on the image data of the third embodiment. Of the image processing of the image conversion unit 352b of the modulation signal generation unit 350b, the operation of the image processing of the deterioration suppression path 392b will be mainly described with reference to FIGS. 40 and 41.

As described above, the second pattern matching unit 384b of the deterioration suppression path 392b sets the target pixels in the image matrix based on the pixel arrangement and pixel values of the first resolution image matrix received from the image matrix acquisition unit 381. , It is determined whether or not the pixel constitutes the contact portion between the corners. Specifically, the second pattern matching unit 384b is a pattern of each of various patterns (for example, patterns CA, CB, etc. shown in FIG. 40 (a)) stored in a buffer memory (not shown) and the acquired image matrix. By performing matching, it is determined whether or not the target pixel included in the image matrix is a pixel constituting a contact portion between corners. Further, the pixel of the pattern stored in the buffer memory has not only the pixel value related to the image information but also the pixel value (“0” or “1”) related to the tag information. Therefore, in the pattern matching by the second pattern matching unit 384b, matching is performed between the pattern and the image matrix for both the pixel value related to the pixel information and the pixel value related to the tag information. Therefore, in pattern matching, for each of the pixels of the image matrix, the pixel value related to the pixel information and the pixel related to the tag information of the pixel corresponding to the pixel in which the pixel value related to the image information in the pattern is "0" and "1". If the values match, the image matrix is determined to match the pattern.

Further, the second pattern matching unit 384b includes a second matching signal indicating the result of determination by pattern matching (for example, which pattern matches) and a target pixel of the image matrix that is the target of pattern matching. The data is sent to the third conversion unit 385b. Further, the second pattern matching unit 384b does not output the second matching signal to the third conversion unit 385b when the image matrix does not match any pattern as a result of the determination by pattern matching. Further, the second pattern matching unit 384b outputs a second enable signal to the first selector unit 387b when the image matrix matches any pattern as a result of determination by pattern matching.

The third conversion unit 385b of the deterioration suppression path 392b sets the target pixel (2400 dpi / 2 bits) of the image data of the first resolution at the second resolution based on the second matching signal received from the second pattern matching unit 384b. It is a functional unit that converts a specific pixel pattern (4800 dpi / 1 bit) and light amount data that defines which pixel of the pixel pattern the light amount is to be strengthened (high exposure). That is, the third conversion unit 385b increases the resolution of the image data of the first resolution to the image data of the second resolution and converts the target pixel into the pixel pattern and the amount of light data, so that the contact portion between the corners. Is left, and deterioration suppression processing is performed to generate light amount data for strengthening the light amount of the pixel related to the remaining contact portion. Specifically, the third conversion unit 385b converts the target pixel of the image data of the first resolution into a pixel pattern corresponding to the pattern indicated by the second matching signal and light intensity data, thereby deteriorating with higher resolution. Perform suppression processing.

When the first selector unit 387b receives the input of the second enable signal from the second pattern matching unit 384b, the first selector unit 387 determines that the target pixel of the image matrix is a pixel constituting the contact portion between the corners, and suppresses deterioration. The second resolution pixel pattern and light amount data obtained by performing the image processing (deterioration suppression processing) of the path 392b are output. Here, the output second resolution pixel pattern and light amount data are shown in the figure in which the target pixel of the first resolution image matrix received from the image matrix acquisition unit 381 by the third conversion unit 385b of the deterioration suppression path 392b is shown in the figure. It is converted into a second resolution pixel pattern and light amount data as shown in 40 (b). In this case, the light amount data is the data in which the light amount of the upper right pixel of the image pattern shown in FIG. 40B is specified to be strengthened (strong exposure).

FIG. 41 shows an example in which the contact portion between the corners is subjected to deterioration suppression processing in units of the second resolution. The image data 1220 shown in FIG. 41 (a) is a partial image (first resolution) including a contact portion between corners, and each pixel of the contact portion between the corners is subjected to a third conversion unit 385b. It is replaced with the converted second resolution pixel pattern and light amount data, and as shown in FIG. 41 (b), the second resolution image data 1221 is generated. As shown in the example of FIG. 41, the edge portion of the black pixel (and not the contact portion between the corners) is thinned by the thinning process by the thinning path 391, whereas it is thinned. The contact portion between the corners is prevented from forming a gap because the contact portion remains by the deterioration suppression treatment by the deterioration suppression path 392b. Further, in the deterioration suppressing process by the deterioration suppressing path 392b, it is specified by the light amount data that defines which pixel of the pixel pattern in which the contact portion between the corners is replaced is to be strengthened (strong exposure). The amount of light of the light source 200 corresponding to the pixel is controlled to be strong.

(About the IL characteristics of the light source and the applied current)
FIG. 42 is a diagram showing IL (Injection property-Light output) characteristics of the applied current of the light source and the light output (light amount). FIG. 43 is a diagram showing the relationship between the magnitudes of the applied currents when the amount of light is varied. FIG. 44 is a diagram showing a state of a line drawing when power modulation is performed by a variable amount of light.

The IL characteristic shown in FIG. 42 is a graph of the relationship (characteristic) between the applied current of the single laser LD of the light source 200 and the light output (light amount). Generally, when the applied current is small, the amount of light of the single laser LD gradually increases due to natural light emission. As the applied current is increased, as shown in FIG. 42, laser oscillation is started at a certain applied current, and the amount of light rapidly increases. The applied current at which the laser oscillation is started is also referred to as an oscillation threshold current (threshold current in FIG. 42, threshold current Is in FIG. 43). After laser oscillation, the relationship between the light emission current (current obtained by subtracting the threshold current from the total applied current) and the amount of light is basically proportional. Therefore, when it is desired to change the amount of light, the applied current may be simply changed.

FIG. 43 shows an image of the applied current when the amount of light is variable. When the emission current Isw_a and the emission light amount P_a shown in FIG. 43A are used as a reference and the emission light amount is multiplied from P_a to P_b, the magnification (P_b / P_a) may be integrated into the emission current Isw_a. That is, in order to obtain the emission light amount P_b, the emission current Isw_b calculated by Isw_b = Isw_a × (P_b / P_a) may be superimposed on the threshold current Is and flowed to the single laser LD.

FIG. 44A schematically shows a line drawing of black pixels having a second resolution based on a normal amount of light (assumed to be 100 [%]). In the case of FIG. 44A, the width of the line drawing actually printed on the recording paper is 65 [μm].

FIG. 44B schematically shows a line drawing of a second resolution black pixel that has been subjected to a thinning process based on a normal amount of light (assumed to be 100 [%]). In the case of FIG. 44 (b), since the line drawing of FIG. 44 (a) is thinned, the line drawing actually printed on the recording paper is 35 [μm], and the line drawing printed on the recording paper is 35 [μm]. Indicates a state in which faintness has occurred.

FIG. 44 (c) shows a second resolution black that has been subjected to a thinning process when the normal amount of light is varied and the amount of light is P [%] higher than 100 [%] (when the exposure is strong). It is a schematic representation of a line drawing of pixels. In the case of FIG. 44 (c), since the line drawing of FIG. 44 (a) is subjected to the thinning process and the strong exposure process, the line drawing actually printed on the recording paper is 52 [μm], which is recorded. It shows a state in which the occurrence of faintness on the line drawing printed on paper is suppressed.

That is, in the deterioration suppressing process of the present embodiment, the process of making a strong exposure is added, so that the faintness (that is, image deterioration) of the printed figure due to the small dots composed of black pixels is suppressed. To.

As described above, in the image data, the edge portion of the black pixel (and not the contact portion between the corners) is thinned by the thinning process by the thinning path 391 to improve the reproducibility of the thin line. On the other hand, for the contact part between the corners, the deterioration suppression process by the deterioration suppression path 392b was performed to leave the contact part and prevent a gap from being generated, and the contact part between the corners was replaced. Among the pixel patterns, the light amount of the light source 200 corresponding to the pixel specified by the light amount data is controlled to be strong. As a result, it is possible to suppress the difficulty of applying toner due to the small dots composed of black pixels, prevent the loss of contacts, and further suppress image deterioration.

(Modified example of the third embodiment)
Next, the image forming apparatus according to the modified example of the third embodiment will be described focusing on the differences from the image forming apparatus according to the third embodiment.

<Deterioration suppression processing>
FIG. 45 is a diagram showing a pattern used for the pattern matching process before the deterioration suppression process is performed on the black characters and the like of the modified example of the third embodiment, and the pixel pattern and the light amount pattern of the black pixels in the deterioration suppression process. is there. FIG. 46 is a diagram illustrating an example of the operation of the thinning process and the deterioration suppressing process on the image data of the modified example of the third embodiment. Of the image processing of the image conversion unit 352b of the modulation signal generation unit 350b, the operation of the image processing of the deterioration suppression path 392b will be mainly described with reference to FIGS. 45 and 46.

The second pattern matching unit 384b of the deterioration suppression path 392b sets the target pixels in the image matrix to corners and corners based on the pixel arrangement and pixel values of the first resolution image matrix received from the image matrix acquisition unit 381. It is determined whether or not the pixels constitute the contact portion of the above. Specifically, the second pattern matching unit 384b is a pattern of each of various patterns (for example, patterns CA, CB, etc. shown in FIG. 45A) stored in a buffer memory (not shown) and the acquired image matrix. By performing matching, it is determined whether or not the target pixel included in the image matrix is a pixel constituting a contact portion between corners. Further, the pixel of the pattern stored in the buffer memory has not only the pixel value related to the image information but also the pixel value (“0” or “1”) related to the tag information. Therefore, in the pattern matching by the second pattern matching unit 384b, matching is performed between the pattern and the image matrix for both the pixel value related to the pixel information and the pixel value related to the tag information. Therefore, in pattern matching, for each of the pixels of the image matrix, the pixel value related to the pixel information and the pixel related to the tag information of the pixel corresponding to the pixel in which the pixel value related to the image information in the pattern is "0" and "1". If the values match, the image matrix is determined to match the pattern.

Further, the second pattern matching unit 384b includes a second matching signal indicating the result of determination by pattern matching (for example, which pattern matches) and a target pixel of the image matrix that is the target of pattern matching. The data is sent to the third conversion unit 385b. Further, the second pattern matching unit 384b does not output the second matching signal to the third conversion unit 385b when the image matrix does not match any pattern as a result of the determination by pattern matching. Further, the second pattern matching unit 384b outputs a second enable signal to the first selector unit 387b when the image matrix matches any pattern as a result of determination by pattern matching.

The third conversion unit 385b of the deterioration suppression path 392b sets the target pixel (2400 dpi / 2 bits) of the image data of the first resolution at the second resolution based on the second matching signal received from the second pattern matching unit 384b. It is a functional unit that converts a specific pixel pattern (4800 dpi / 1 bit) and light amount data that defines which pixel of the pixel pattern the light amount is to be strengthened (high exposure). That is, the third conversion unit 385b increases the resolution of the image data of the first resolution to the image data of the second resolution and converts the target pixel into the pixel pattern and the amount of light data, so that the contact portion between the corners. Is left, and deterioration suppression processing is performed to generate light amount data for strengthening the light amount of the pixel related to the remaining contact portion. Specifically, the third conversion unit 385b converts the target pixel of the image data of the first resolution into a pixel pattern corresponding to the pattern indicated by the second matching signal and light intensity data, thereby deteriorating with higher resolution. Perform suppression processing. In this modification, as shown in FIG. 45B, the pixel pattern corresponding to the pattern indicated by the second matching signal is simply the case where the resolution conversion process is executed for the target pixel of the first resolution. It has a similar pixel pattern.

When the first selector unit 387b receives the input of the second enable signal from the second pattern matching unit 384b, the first selector unit 387 determines that the target pixel of the image matrix is a pixel constituting the contact portion between the corners, and suppresses deterioration. The second resolution pixel pattern and light amount data obtained by performing the image processing (deterioration suppression processing) of the path 392b are output. Here, the output second resolution pixel pattern and light amount data are shown in the figure in which the target pixel of the first resolution image matrix received from the image matrix acquisition unit 381 by the third conversion unit 385b of the deterioration suppression path 392b is shown in the figure. It is converted into a second resolution pixel pattern and light amount data as shown in 45 (b). In this case, the light amount data is the data in which the light amount of the upper left, upper right, and lower right pixels of the image pattern shown in FIG. 45B is specified to be strengthened (strong exposure).

FIG. 46 shows an example in which the contact portion between corners is subjected to deterioration suppression processing in units of the second resolution. The image data 1230 shown in FIG. 46A is a partial image (first resolution) including a contact portion between corners, and each pixel of the contact portion between the corners is subjected to a third conversion unit 385b. It is replaced with the converted second resolution pixel pattern and light amount data, and as shown in FIG. 46 (b), the second resolution image data 1231 is generated. In this case, as shown in FIG. 45B, the pixel pattern to be replaced is simply the same pixel pattern as when the resolution conversion process is executed on the target pixel of the first resolution. As shown in the example of FIG. 46, the edge portion of the black pixel (and not the contact portion between the corners) is thinned by the thinning process by the thinning path 391. The contact portion between the corners is prevented from forming a gap because the contact portion remains by the deterioration suppression treatment by the deterioration suppression path 392b. Further, in the deterioration suppression process by the deterioration suppression path 392b of this modification, the light amount data that defines which pixel of the pixel pattern in which the contact portion between the corners is replaced is to be strengthened (strong exposure). The amount of light of the light source 200 corresponding to the pixel specified by is controlled to be strong. Further, since the light intensity data in this case stipulates that the exposure should be strong for more pixels than in the case shown in FIG. 40, it is difficult for the toner to get on due to the small dots composed of the black pixels. Can be further suppressed, the loss of contacts can be prevented, and image deterioration can be further suppressed.

In each of the above-described embodiments and modifications, in the thinning process of the thinning path 391 and the deterioration suppressing process of the deterioration suppressing pass 392 (392b), the pattern matches the image matrix of the target pixel of the first resolution. By associating a specific pixel pattern (and light intensity data) of the second resolution of the above, the strength of thinning and deterioration suppression is given, but the present invention is not limited to this. For example, the strength of thinning and deterioration suppression may be controlled based on an external signal input to the image conversion unit 352 (352a, 352b). Specifically, for example, a second resolution pixel pattern (and light amount data) to be converted with respect to a first resolution target pixel is performed according to the presence or absence of an external signal input or the type of the input external signal. It may be changed. Alternatively, although the same pixel pattern of the second resolution to be converted for the target pixel of the first resolution is applied, the arrangement of the pixel patterns (and the amount of light data) is changed according to the input external signal. May be good.

Further, in each of the above-described embodiments and modifications, when at least one of the functional units of the light source control device 110 of the image forming apparatus is realized by executing a program, the program is provided by being incorporated in a ROM or the like in advance. Will be done. Further, the program executed by the image forming apparatus according to each of the above-described embodiments and modifications is a CD-ROM (Computer Disc-ROM), a flexible disk (FD), or a file in an installable format or an executable format. It may be configured to be recorded and provided on a computer-readable recording medium such as a CD-R (Compact Disk-Recordable) or a DVD (Digital Versaille Disc). Further, the program executed by the image forming apparatus according to each of the above-described embodiments and modifications is stored on a computer connected to a network such as the Internet and provided by downloading via the network. May be good. Further, the program executed by the image forming apparatus according to each of the above-described embodiments and modifications may be configured to be provided or distributed via a network such as the Internet. Further, the program executed by the image forming apparatus according to each of the above-described embodiments and modifications has a module configuration including at least one of the above-mentioned functional units, and the CPU is described above as the actual hardware. By reading the program from the ROM of the above and executing the program, each of the above-mentioned functional units is loaded on the main storage device and generated.

1 Image forming device 2 Upper device 10 Photodetector 30, 30a to 30d Photoreceptor drum 31, 31a to 31d Cleaning unit 32, 32a to 32d Charging device 33, 33a to 33d Development roller 34, 34a to 34d Toner cartridge 40 Transfer belt 42 Transfer roller 45 Concentration detector 46, 46a to 46d Home position sensor 50 Fixing roller 54 Feed roller 56 Resist roller vs. 58 Paper discharge roller 60 Paper feed tray 70 Paper discharge tray 80 Communication control device 90 Printer control device 104 Polygon mirror 105 , 105a-105d Scanning lens 106a-106d Folded mirror 108b, 108c Folded mirror 110 Light source controller 200, 200a-200d Light source 201, 201a-201d Coupling lens 202, 202a-202d Opening plate 204, 204a-204d Cylindrical lens 250 light Detector 300 Interface unit 320 Image processing unit 321 Attribute separation unit 322 Color conversion unit 323 Black ink generation unit 324 Gamma correction unit 325 Tag generation unit 326 Position correction unit 327 Gradation processing unit 330 Cable 340, 340b Drive control unit 350, 350b Modulation Signal generator 351 Buffer memory 352, 352a, 352b Image converter 353, 353b Gamma converter 360 Clock generator 370, 370b Light source drive 371 Variable magnification value holder 372 Power modulation current setting 373 Normal current setting 374 Threshold current Setting unit 375 Second selector unit 376 Integrated light amount calculation unit 376a LPF
376b ADC
377a, 377b DAC
378a, 378b Current source 379a, 379b Switch 381 Image matrix acquisition unit 382 1st pattern matching unit 383 1st conversion unit 384, 384a, 384b 2nd pattern matching unit 385, 385b 3rd conversion unit 386 2nd conversion unit 387, 387a Selector section 387b 1st selector section 391 Thinning path 392, 392b Deterioration suppression path 393 Resolution conversion path 400 CPU
401 RAM
402 Flash memory 403 I / F circuit 404 Bus 1000, 1001 Image data 1010, 1011 Image data 1100, 1101 Image data 1200, 1201, 1210, 1211 Image data 1220, 1221, 1230, 1231 Image data LD Single laser

Japanese Unexamined Patent Publication No. 2009-21546

Claims (12)

A first matching unit that determines whether or not the image matrix of the image data of the first resolution matches any one or more predetermined first patterns indicating the edge portion.
The target pixel of the first resolution of the image matrix determined by the first matching unit to match the first pattern is associated with the first pattern having a second resolution higher than the first resolution. A thinning converter that replaces the first pixel pattern and performs thinning processing,
A second matching unit that determines whether or not the image matrix of the first resolution image data matches any one or more predetermined second patterns indicating the contact portions.
Wherein the target pixel, Rukoto the corner and the corner replaced by a second pixel pattern of the second resolution corresponding to the second pattern of the determined image matrix and the second matching unit matches the second pattern A suppression conversion unit that performs deterioration suppression processing that leaves the contact part with
Based on the determination result by the first matching unit and the determination result by the second matching unit, the image data of the second resolution output from the thinning conversion unit or the suppression conversion unit output the image data. A selection unit that selects and outputs the second resolution image data, and
Image processing device equipped with. The image processing apparatus according to claim 1, wherein the suppression conversion unit performs a process of replacing the target pixel with the second pixel pattern in the deterioration suppression process so as not to leave a gap between black pixels. The image according to claim 1 or 2, wherein the suppression conversion unit performs resolution conversion processing for replacing the target pixel of the first resolution with the pixel of the second resolution which is the same as the target pixel as the deterioration suppression processing. Processing device. A resolution conversion unit that performs a resolution conversion process for converting the image data of the first resolution to the image data of the second resolution is further provided.
The selection unit is the second resolution image data output from the thinning conversion unit based on the determination result by the first matching unit and the determination result by the second matching unit, from the resolution conversion unit. The image processing apparatus according to claim 1 or 2, wherein the output image data of the second resolution or the image data of the second resolution output from the suppression conversion unit is selected and output. As the deterioration suppressing process, the suppression conversion unit uses the target pixel of the image matrix determined by the second matching unit to match the second pattern with the second pixel pattern corresponding to the second pattern. The image processing apparatus according to claim 4, wherein the image processing apparatus is replaced with light amount data that defines which pixel of the second pixel pattern the light amount is to be enhanced. When the image matrix determines that the image matrix matches the first pattern, the first matching unit outputs a first enable signal to the selection unit.
When the image matrix determines that the image matrix matches the second pattern, the second matching unit outputs a second enable signal to the selection unit.
When the second enable signal is input, the selection unit converts the image data of the second resolution output from the suppression conversion unit into the thinning conversion unit regardless of the state of the first enable signal. The image processing apparatus according to any one of claims 1 to 5, which is selected with priority over the image data of the second resolution output from. The image data of the first resolution includes a first pixel value of the image information and a second pixel value indicating tag information corresponding to the attribute information of the image data.
The first matching unit determines whether or not the image matrix of the first resolution matches the first pattern including the first pixel value and the second pixel value.
The second matching unit is any one of claims 1 to 6 for determining whether or not the image matrix of the first resolution matches the second pattern including the first pixel value and the second pixel value. The image processing apparatus according to paragraph 1. The image processing apparatus according to any one of claims 1 to 7.
A pulse generator that generates a modulated pulse signal, which is a signal for controlling the lighting of a light source, from the image data of the second resolution output from the image processing device.
A light source driving unit that drives the light source in response to the modulated pulse signal generated by the pulse generating unit, and a light source driving unit.
Drive control device equipped with. The drive control device according to claim 8, wherein the image processing device, the pulse generation unit, and the light source drive unit are composed of a single integrated device. The interface part that acquires image data and
A processing unit that performs predetermined image processing on the image data acquired by the interface unit to obtain the image data of the first resolution, and a processing unit.
The drive control device according to claim 8 or 9, which receives the image data of the first resolution that has been image-processed by the processing unit.
Light source control device equipped with. The light source control device according to claim 10 and
The light source driven and controlled by the light source control device,
A forming portion that forms a latent image on the photoconductor with a latent image corresponding to the image data of the second resolution by the light emitted by the light source.
An image forming apparatus equipped with. A first matching step for determining whether or not the image matrix of the first resolution image data matches any one or more predetermined first patterns indicating the edge portion.
The target pixel of the first resolution of the image matrix determined to match the first pattern is replaced with a first pixel pattern associated with the first pattern, which has a second resolution higher than the first resolution. The thinning conversion step that performs the thinning process and
A second matching step for determining whether or not the image matrix of the first resolution image data matches any one or more predetermined second patterns indicating the contact portions.
Degradation to leave the target pixel, the contact portion between the corner and the corner by Rukoto replaced by a second pixel pattern of the second resolution corresponding to the second pattern image matrix is determined that matches the second pattern Suppression conversion step to perform suppression processing and
Based on the determination result by the first matching step and the determination result by the second matching step, the image data of the second resolution output by the thinning conversion step or the first output by the suppression conversion step. A selection step that selects and outputs 2-resolution image data, and
Image processing method having.

Images