JP6673019B2 - Image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming method.

  Conventionally, a method of forming an image using an electrophotographic process or the like has been known.

  For example, whether an image forming apparatus that forms an image in accordance with light emitted from a light source first performs image processing of the first resolution and image processing associated with each pixel of the first resolution image data And an image processing unit for generating tag information indicating whether or not the tag information is included. Next, the image forming apparatus converts the image data of the first resolution into image data of a second resolution higher than the first resolution. Then, the image forming apparatus drives the light source based on the modulation signal corresponding to the second resolution image data. Further, the image forming apparatus specifies a target pixel to be subjected to image processing among the pixels included in the image data of the first resolution based on the tag information. Subsequently, the image forming apparatus generates a second resolution image-processed pixel pattern according to the target pixel. Then, when the image forming apparatus converts the first resolution image data into the second resolution image data, the image forming apparatus converts the target pixel in the first resolution image data into the generated image-processed pixel pattern. Thus, there is known a method capable of executing image processing at a high resolution without increasing the data transfer amount of image data (for example, see Patent Document 1).

  However, in some cases, the conventional method cannot adjust the aspect ratio of a line or a character on which an image is formed.

  An object of one aspect of the present invention is to improve image quality by adjusting the aspect ratio of a line or a character on which an image is formed, or the like.

In order to solve the above-described problems, an image forming apparatus which performs image formation using a light source, which is one embodiment of the present invention,
Receives first image data having a plurality of first pixels indicating whether the light source is turned on or off, or a density at which an image is formed, and tag data indicating respective attributes of the first pixels. A data receiving unit;
A specific data setting unit that sets specific data that can specify a first target pixel to be changed among the first pixels;
A first setting unit that sets a first number of pixels to be turned off in a first direction;
A second setting unit that sets a second number of pixels to be turned off in a second direction orthogonal to the first direction;
In the conversion of the first image data to the second image data having a higher resolution than the first image data, based on the specific data and the tag data, among the second pixels included in the second image data, A second target pixel corresponding to a first target pixel is specified, and a part or all of the second target pixel is set as a pixel for turning off the light source based on the first pixel number and the second pixel number. A conversion unit for generating two image data;
An image forming unit that controls the light source to form an image based on the second image data.

  The image quality can be improved by adjusting the aspect ratio of lines or characters on which an image is formed, or the like.

FIG. 1 is a diagram illustrating an example of a schematic configuration of an image forming apparatus according to an embodiment of the present disclosure. It is a figure showing an example of a position sensor concerning one embodiment of the present invention. FIG. 4 is a diagram illustrating an example of an installation position of a density detection unit that detects the density of an image according to an embodiment of the present disclosure. FIG. 5 is a diagram illustrating an example of a method for detecting the density of an image according to an embodiment of the present invention. FIG. 1 is a diagram (part 1) illustrating an example of an optical scanning control device according to an embodiment of the present invention. FIG. 2 is a diagram (part 2) illustrating an example of an optical scanning control device according to an embodiment of the present invention. FIG. 3 is a diagram (part 3) illustrating an example of the optical scanning control device according to the embodiment of the present invention. FIG. 4 is a diagram (part 4) illustrating an example of an optical scanning control device according to an embodiment of the present invention. FIG. 1 is a block diagram illustrating an example of a hardware configuration of an image forming apparatus according to an embodiment of the present disclosure. 6 is a flowchart illustrating an example of an entire process performed by the image forming apparatus according to the embodiment of the present disclosure. FIG. 4 is a diagram illustrating an example of specific data according to an embodiment of the present invention. It is a figure (the 1) showing an example of a pixel specified based on specific data concerning one embodiment of the present invention. FIG. 7 is a diagram (part 2) illustrating an example of a pixel specified based on the specified data according to an embodiment of the present invention. FIG. 8 is a diagram (part 3) illustrating an example of a pixel specified based on the specified data according to an embodiment of the present invention. FIG. 9 is a diagram (part 4) illustrating an example of a pixel specified based on the specific data according to an embodiment of the present invention. 5 is a timing chart illustrating an example of reception of first image data and tag data according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a first example of conversion according to an embodiment of the present invention. FIG. 9 is a diagram illustrating a second example of conversion according to an embodiment of the present invention. FIG. 11 is a diagram illustrating a third example of conversion according to an embodiment of the present invention. It is a figure showing the 4th example of conversion concerning one embodiment of the present invention. FIG. 4 is a diagram illustrating a first example of a double density process performed by the image forming apparatus according to the embodiment of the present disclosure. FIG. 7 is a diagram illustrating a second example of the double density processing by the image forming apparatus according to the embodiment of the present disclosure. FIG. 6 is a diagram illustrating a third example of the double density process performed by the image forming apparatus according to the embodiment of the present disclosure. FIG. 11 is a diagram illustrating a fourth example of the double density process performed by the image forming apparatus according to the embodiment of the present disclosure. FIG. 11 is a diagram illustrating a fifth example of the double density process performed by the image forming apparatus according to the embodiment of the present disclosure. FIG. 9 is a diagram illustrating a comparative example in the double density processing by the image forming apparatus. FIG. 5 is a diagram illustrating an example of a processing result of a double density process performed by the image forming apparatus according to the embodiment of the present disclosure. FIG. 4 is a diagram illustrating a first example of conversion of multi-bit data according to an embodiment of the present invention. FIG. 6 is a diagram illustrating a second example of multi-bit data conversion according to an embodiment of the present invention. FIG. 9 is a diagram illustrating a third example of multi-bit data conversion according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of pattern matching performed by the image forming apparatus according to the embodiment of the present disclosure. FIG. 4 is a diagram illustrating a first example of a smoothing process and a thinning process performed by the image forming apparatus according to the embodiment of the present disclosure. FIG. 5 is a diagram illustrating a second example of the smoothing process and the thinning process performed by the image forming apparatus according to the embodiment of the present disclosure. FIG. 1 is a diagram illustrating an example of a functional configuration of an image forming apparatus according to an embodiment of the present disclosure.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description will be omitted.

<Example of image forming apparatus>
FIG. 1 is a diagram illustrating an example of a schematic configuration of an image forming apparatus according to an embodiment of the present disclosure. Hereinafter, a color printer 2000 which is an example of the illustrated image forming apparatus will be described as an example. In this example, the color printer 2000 forms a full-color image on a recording medium such as paper by superimposing four colors. The four colors are, for example, black (K), cyan (C), magenta (M), and yellow (Y). Hereinafter, each color may be indicated by “K”, “C”, “M”, and “Y”, respectively. Thus, the color printer 2000 is a so-called tandem-type multicolor color printer.

  Further, as shown in the figure, in the three-dimensional orthogonal coordinate system, the longitudinal direction of each photoconductor is referred to as “Y axis”. The direction orthogonal to the “Y axis” and in which the photosensitive drums are arranged is referred to as “X axis”. Further, a direction orthogonal to the “X axis” and “Y axis” and corresponding to a so-called vertical direction is defined as “Z axis”. In the following description, the Y-axis direction may be referred to as “main scanning direction”, and the X-axis direction may be referred to as “sub-scanning direction”.

  The color printer 2000 includes a light scanning controller 2010 having a light source and an optical system for scanning light emitted from the light source. That is, the optical scanning control device 2010 is a so-called exposure device. The color printer 2000 includes photoconductor drums 2030a, 2030b, 2030c, and 2030d for each color. The color printer 2000 includes cleaning units 2031a, 2031b, 2031c, and 2031d for each of the photosensitive drums. Similarly, the color printer 2000 includes charging devices 2032a, 2032b, 2032c, and 2032d. Further, the color printer 2000 includes developing rollers 2033a, 2033b, 2033c, and 2033d. Furthermore, the color printer 2000 includes toner cartridges 2034a, 2034b, 2034c, and 2034d.

  In addition, the color printer 2000 includes a transfer belt 2040, a transfer roller 2042, a fixing roller 2050, a paper feed roller 2054, a registration roller pair 2056, a paper discharge roller 2058, and the like. The color printer 2000 includes a paper feed tray 2060, a paper discharge tray 2070, a communication control device 2080, a density detector 2245, and the like.

  The color printer 2000 includes home position sensors 2246a, 2246b, 2246c, and 2246d. Further, the color printer 2000 includes a potential control unit and a printer control device 2090 that controls the hardware.

  In the following description, any four photosensitive drums 2030a, 2030b, 2030c, and 2030d are not distinguished, and any one of the photosensitive drums may be referred to as a "photosensitive drum 2030". Similarly, in the following description, any four developing rollers 2033a, 2033b, 2033c, and 2033d are not distinguished, and any one of the developing rollers may be referred to as a “developing roller 2033”.

  The color printer 2000 is connected to a higher-level device such as a PC (Personal Computer) via a network or the like. Further, the color printer 2000 can bidirectionally communicate with an external device such as a host device via a network or the like by the communication control device 2080.

  The printer control device 2090 has a CPU (Central Processing Unit) which is an example of an arithmetic device and a control device. Further, the printer control device 2090 has a ROM (Read-Only Memory) as an example of a storage device that stores a program for executing various processes by the CPU and various data used by the CPU. Further, the printer control device 2090 has a RAM (Random Access Memory) as an example of a main storage device serving as a work area of the CPU. Furthermore, the printer control device 2090 has an A / D (analog-digital) conversion circuit for converting analog data into digital data.

  Further, the photosensitive drum 2030a, the charging device 2032a, the developing roller 2033a, the toner cartridge 2034a, and the cleaning unit 2031a constitute an image forming station used as a set for forming a black image. Hereinafter, it may be referred to as “K station”.

  Similarly, the photosensitive drum 2030b, the charging device 2032b, the developing roller 2033b, the toner cartridge 2034b, and the cleaning unit 2031b constitute an image forming station used as a set for forming a cyan image. Hereinafter, it may be referred to as “C station”.

  Further, the photosensitive drum 2030c, the charging device 2032c, the developing roller 2033c, the toner cartridge 2034c, and the cleaning unit 2031c constitute an image forming station used as a set for forming a magenta image. Hereinafter, it may be referred to as “M station”.

  The photosensitive drum 2030d, the charging device 2032d, the developing roller 2033d, the toner cartridge 2034d, and the cleaning unit 2031d form an image forming station used as a set for forming a yellow image. Hereinafter, it may be referred to as “Y station”.

  In the following description, any arbitrary image forming station may be simply referred to as “station” without distinguishing between “K station”, “C station”, “M station”, and “Y station”.

  Each photosensitive drum has a photosensitive layer on the surface. That is, each surface of each photoconductor drum is a surface to be scanned with light from a light source. The photosensitive drum is rotated in the direction of the arrow by a rotating mechanism or the like as shown in the figure.

  Each charging device charges the surface of each photosensitive drum.

  For example, upon receiving a request from a host device or the like, the printer control device 2090 controls each hardware and sends image data transmitted from the host device or the like to the optical scanning control device 2010.

  The optical scanning control device 2010 irradiates a light beam modulated for each color to the surface of each photosensitive drum of each color based on the image data. When light is irradiated, the charge of the light-irradiated portion on each surface of each photoconductor disappears. Therefore, when the light is irradiated, a latent image indicated by the image data is formed on each surface of each photoconductor. This latent image moves to each developing roller by rotation of the photosensitive drum. The details of the optical scanning control device 2010 will be described later. An area where writing is performed based on image data, that is, an area where a latent image can be formed may be referred to as an “effective scanning area”, an “image forming area”, an “effective image area”, or the like.

  Black toner is stored in the toner cartridge 2034a. This black toner is supplied to the developing roller 2033a. Similarly, cyan toner is stored in the toner cartridge 2034b. This cyan toner is supplied to the developing roller 2033b. The toner cartridge 2034c stores magenta toner. This magenta toner is supplied to the developing roller 2033c. Further, yellow toner is stored in the toner cartridge 2034d. This yellow toner is supplied to the developing roller 2033d.

  When each developing roller rotates, each toner is applied to each surface of each photosensitive drum from each toner cartridge. When the toner of each developing roller comes into contact with the surface of each photosensitive drum, the toner may adhere to the photosensitive drum. In this case, each surface of the photosensitive drum is irradiated with light from a light source. That is, each developing roller causes toner to adhere to a latent image formed on each surface of each photoconductor, thereby visualizing the latent image. Next, an image formed by attaching toner, a so-called toner image, is transferred to the transfer belt 2040 by rotation of each photosensitive drum. Such charging, formation of a latent image, and transfer are performed for each color. Subsequently, the black, cyan, magenta, and yellow toner images are sequentially transferred onto the transfer belt 2040 at a predetermined timing. As described above, when the toner images of the respective colors are transferred, the respective toner images overlap. Then, a color image is formed.

  On the other hand, a recording medium such as paper is stored in the paper feed tray 2060. In the vicinity of the paper feed tray 2060, a paper feed roller 2054 is arranged. The paper feed roller 2054 takes out paper and the like one by one from the paper feed tray 2060. Next, the extracted paper or the like is transported to the registration roller pair 2056. Subsequently, the registration roller pair 2056 sends the conveyed paper or the like between the transfer belt 2040 and the transfer roller 2042 at a predetermined timing. As a result, the color image formed on the transfer belt 2040 is transferred to the paper or the like to be fed. Next, the paper or the like on which the color image has been transferred is sent to the fixing roller 2050.

  In the fixing roller, heat and pressure are applied to paper or the like. As described above, when heat and pressure are applied, the toner is fixed on the paper or the like on which the color image is transferred. Next, when the fixing is completed, the paper and the like are sent to a paper discharge tray 2070 via a paper discharge roller 2058. In the paper discharge tray 2070, paper and the like are sequentially stacked.

  Each cleaning unit removes toner remaining on each surface of each photosensitive drum, that is, so-called residual toner. When the residual toner is removed in this way, the photosensitive drum returns to the position where the charging device faces. Therefore, the color printer 2000 can perform the next image formation.

  The color printer 2000 has a home position sensor for detecting a predetermined position (hereinafter, “home position”) of the photosensitive drum for each photosensitive drum.

  FIG. 2 is a diagram showing an example of the position sensor according to one embodiment of the present invention. As shown, the position sensor includes, for example, a light source LG such as an LED (Light Emitting Diode), a fixed slit SL, a light receiving element LRE, and a waveform shaping circuit CIR. In the illustrated example, the photosensitive drum 2030 has a hole, and the light emitted from the light source LG passes through the hole and the fixed slit SL, and is detected by the light receiving element LRE. This detection result is indicated by the output waveform of the waveform shaping circuit CIR as shown. Although the illustrated configuration is configured to detect transmitted light, for example, the light receiving element LRE may be configured to detect reflected light.

  In addition, first, for example, a mark or a protrusion is provided on the photosensitive drum to indicate the home position. If such a mark or the like is present, even if the photoconductor drum rotates, if the mark or the like is detected, the color printer 2000 returns to the home position by rotating the photoconductor drum once from the home position. You can see that. The home position sensor is a sensor that detects the home position by electrical, mechanical, or a combination thereof. For example, when the home position is marked with a projection or the like, the home position sensor is a touch sensor or the like that mechanically detects the projection or the like. On the other hand, when the home position is marked with a mark or the like, the home position sensor is an optical sensor or the like that electrically detects the mark or the like.

  The color printer 2000 detects the home position of each photosensitive drum by using the home position sensors 2246a, 2246b, 2246c and 2246d. Specifically, home position sensor 2246a detects the rotation home position of photoconductor drum 2030a. Similarly, home position sensor 2246b detects the rotation home position of photosensitive drum 2030b. The home position sensor 2246c detects the rotation home position of the photosensitive drum 2030c. Further, the home position sensor 2246d detects the rotation home position of the photosensitive drum 2030d.

  The color printer 2000 has a potential sensor for measuring the surface of each photosensitive drum and indicating the surface potential of the photosensitive drum 2030 for each photosensitive drum. The potential sensor is installed, for example, at a position facing each photosensitive drum.

<Example of concentration detector>
FIG. 3 is a diagram illustrating an example of an installation position of a density detection unit that detects the density of an image according to an embodiment of the present invention. For example, the concentration detector 2245 (FIG. 1) has five optical sensors P1, P2, P3, P4, and P5 as shown. Hereinafter, an example will be described in which the density detector 2245 has five optical sensors. Note that the density detector 2245 is not limited to having five optical sensors, and may have a configuration having three optical sensors, for example.

  In the following description, any of the optical sensors P1, P2, P3, P4, and P5 may be simply referred to as an “optical sensor” without distinction.

  Specifically, the optical sensors P1, P2, P3, P4, and P5c are respectively provided at positions that become effective image areas in the Y axis, that is, the direction orthogonal to the traveling direction of the transfer belt 2040, as illustrated. .

  FIG. 4 is a diagram illustrating an example of a method for detecting the density of an image according to an embodiment of the present invention. Using the optical sensors P1, P2, P3, P4, and P5 installed as shown in FIG. 3, the density detector 2245 (FIG. 1) detects the density, for example, as shown in FIG. Hereinafter, an example of the optical sensor P1 will be described.

  The concentration detector 2245 has a light source such as the LED 11. First, light is emitted from the LED 11 to the transfer belt 2040. This light is reflected on the transfer belt 2040 or a toner image formed on the transfer belt 2040. The reflected light is received by the optical sensor P1, for example, when the reflection is specular reflection. Next, the optical sensor P1 outputs a signal indicating the amount of received light based on the received light. That is, since the light receiving amount indicated by the signal differs depending on the toner amount of the transfer belt 2040 and the like, the color printer can detect the density based on the signal.

  Note that a plurality of optical sensors P1 may be provided as illustrated. Specifically, the light may be reflected so as to diffuse on the transfer belt 2040 or the like. Therefore, the color printer may include the optical sensor 13 for diffuse reflection. Note that, similarly to the optical sensor P1, the diffuse reflection optical sensor 13 outputs a signal indicating the amount of received light when receiving light. Specifically, for example, in the case of color, the toner amount is calculated using the specular reflection light and the diffuse reflection light. On the other hand, in the case of black, the toner amount is calculated using regular reflection.

<Example of optical scanning control device>
FIG. 5 is a diagram (part 1) illustrating an example of an optical scanning control device according to an embodiment of the present invention.

  FIG. 6 is a diagram (part 2) illustrating an example of the optical scanning control device according to the embodiment of the present invention.

  FIG. 7 is a diagram (part 3) illustrating an example of the optical scanning control device according to the embodiment of the present invention.

  FIG. 8 is a diagram (part 4) illustrating an example of the optical scanning control device according to the embodiment of the present invention.

  For example, the optical scanning control device 2010 includes light sources 2200a, 2200b, 2200c, and 2200d. Further, the optical scanning control device 2010 includes coupling lenses 2201a, 2201b, 2201c and 2201d. Further, the optical scanning control device 2010 has aperture plates 2202a, 2202b, 2202c and 2202d. Furthermore, the optical scanning control device 2010 includes cylindrical lenses 2204a, 2204b, 2204c, and 2204d. In addition, the optical scanning control device 2010 includes a polygon mirror 2104, scanning lenses 2105a, 2105b, 2105c, and 2105d, and folding mirrors 2106a, 2106b, 2106c, 2106d, 2108b, and 2108c.

  In the following description, any one of the light sources 2200a, 2200b, 2200c, and 2200d may be referred to as a “light source 2200” without distinction.

  The light source 2200 includes, for example, a surface emitting laser array in which a plurality of (for example, 40) light emitting units are two-dimensionally arranged. The plurality of light emitting units included in the surface emitting laser array are arranged such that, for example, when all the light emitting units project in the sub-scanning direction, the intervals between the light emitting units are equal. That is, the plurality of light emitting units are arranged so as to have an interval at least in the sub-scanning direction. In the following description, the distance between the centers of any two light emitting units may be referred to as “light emitting unit interval”.

  The coupling lens 2201a is arranged on the optical path of the light beam emitted from the light source 2200a. The coupling lens 2201a converts this light beam into a substantially parallel light beam. Similarly, coupling lens 2201b is arranged on the optical path of the light beam emitted from light source 2200b. The coupling lens 2201b converts this light beam into a substantially parallel light beam. Further, the coupling lens 2201c is arranged on the optical path of the light beam emitted from the light source 2200c. The coupling lens 2201c converts this light beam into a substantially parallel light beam. Furthermore, the coupling lens 2201d converts this light beam into a substantially parallel light beam. Further, the coupling lens 2201d is arranged on the optical path of the light beam emitted from the light source 2200d.

  The aperture plate 2202a has an opening and shapes a light beam passing through the coupling lens 2201a. Similarly, the aperture plate 2202b has an opening, and shapes a light beam passing through the coupling lens 2201b. Further, the aperture plate 2202c has an aperture, and shapes the light beam passing through the coupling lens 2201c. Furthermore, the aperture plate 2202d has an opening, and shapes a light beam passing through the coupling lens 2201d.

  The cylindrical lens 2204a forms an image of a light beam passing through the opening of the aperture plate 2202a in the vicinity of the deflecting reflection surface of the polygon mirror 2104 in the Z-axis direction. Similarly, the cylindrical lens 2204b forms an image of a light beam passing through the opening of the aperture plate 2202b in the vicinity of the deflecting reflection surface of the polygon mirror 2104 in the Z-axis direction. Further, the cylindrical lens 2204c forms an image of the light beam passing through the opening of the aperture plate 2202c in the vicinity of the deflecting reflection surface of the polygon mirror 2104 in the Z-axis direction. Further, the cylindrical lens 2204d forms an image of the light beam passing through the opening of the aperture plate 2202d in the vicinity of the deflecting reflection surface of the polygon mirror 2104 in the Z-axis direction.

  The optical system including the coupling lens 2201a, the aperture plate 2202a, and the cylindrical lens 2204a becomes a front optical system in the deflector of the K station. Similarly, the optical system including the coupling lens 2201b, the aperture plate 2202b, and the cylindrical lens 2204b becomes a front optical system in the deflector of the C station. Further, the optical system including the coupling lens 2201c, the aperture plate 2202c, and the cylindrical lens 2204c becomes a front optical system in the deflector of the M station. Furthermore, the optical system including the coupling lens 2201d, the aperture plate 2202d, and the cylindrical lens 2204d becomes a front optical system in the deflector of the Y station.

  The polygon mirror 2104 rotates around the Z axis. As shown, the polygon mirror 2104 has a two-stage structure in the Z-axis direction. Further, the polygon mirror 2104 has a four-sided mirror. The four-sided mirrors of the polygon mirror 2104 serve as respective deflecting and reflecting surfaces. Then, in the first-stage four-sided mirror, the light beam from the cylindrical lens 2204b and the light beam from the cylindrical lens 2204c are respectively deflected. On the other hand, in the second-stage four-sided mirror, the light beam from the cylindrical lens 2204a and the light beam from the cylindrical lens 2204d are respectively deflected. It is assumed that the light beam from the cylindrical lens 2204a and the light beam from the cylindrical lens 2204b are deflected from the position of the polygon mirror 2104 toward the "-" side on the X axis. On the other hand, it is assumed that the light beam from the cylindrical lens 2204c and the light beam from the cylindrical lens 2204d are deflected from the position of the polygon mirror 2104 toward the “+” side on the X axis.

  Each scanning lens focuses each light beam on each photosensitive drum. Further, based on the rotation of the polygon mirror 2104, control is performed such that the light spot moves on the surface of each photosensitive drum at a constant speed in the main scanning direction.

  Specifically, first, the scanning lens 2105a and the scanning lens 2105b are arranged on the “−” side in the X axis from the position of the polygon mirror 2104. On the other hand, the scanning lens 2105c and the scanning lens 2105d are arranged on the “+” side on the X axis with respect to the position of the polygon mirror 2104.

  Further, the scanning lens 2105a and the scanning lens 2105b are stacked in the Z-axis direction. Further, the scanning lens 2105b is installed at a position facing the first-stage four-sided mirror. On the other hand, the scanning lens 2105a is installed at a position facing the second-stage four-sided mirror. Similarly, the scanning lens 2105c and the scanning lens 2105d are stacked in the Z-axis direction. Further, the scanning lens 2105c is installed at a position facing the first-stage four-sided mirror. On the other hand, the scanning lens 2105d is installed at a position facing the second-stage four-sided mirror.

  The light beam from the cylindrical lens 2204a deflected by the polygon mirror 2104 is applied to the photosensitive drum 2030a via the scanning lens 2105a and the return mirror 2106a. As described above, when light is irradiated on the photosensitive drum 2030a by the light beam, a light spot is formed. This light spot moves in the longitudinal direction of the photosensitive drum 2030a when the polygon mirror 2104 rotates. That is, the light spot scans the photosensitive drum 2030a based on the rotation of the polygon mirror 2104.

  The direction in which the light spot moves is the main scanning direction. Therefore, the direction in which the photosensitive drum 2030a rotates is the sub-scanning direction.

  Similarly, a light beam deflected by the polygon mirror 2104 from the cylindrical lens 2204b is applied to the photosensitive drum 2030b via the scanning lens 2105b and the return mirror 2106b. As described above, when light is irradiated on the photosensitive drum 2030b by the light beam, a light spot is formed. This light spot moves in the longitudinal direction of the photosensitive drum 2030b when the polygon mirror 2104 rotates. That is, the light spot scans the photosensitive drum 2030b based on the rotation of the polygon mirror 2104.

  The direction in which the light spot moves is the main scanning direction. Therefore, the direction in which the photosensitive drum 2030b rotates is the sub-scanning direction.

  Similarly, a light beam from the cylindrical lens 2204c deflected by the polygon mirror 2104 is applied to the photosensitive drum 2030c via the scanning lens 2105c and the return mirror 2106c. As described above, when light is irradiated on the photosensitive drum 2030c by the light beam, a light spot is formed. This light spot moves in the longitudinal direction of the photosensitive drum 2030c when the polygon mirror 2104 rotates. That is, the light spot scans on the photosensitive drum 2030c based on the rotation of the polygon mirror 2104.

  The direction in which the light spot moves is the main scanning direction. Therefore, the direction in which the photosensitive drum 2030c rotates is the sub-scanning direction.

  Similarly, a light beam deflected by the polygon mirror 2104 from the cylindrical lens 2204d is applied to the photosensitive drum 2030d via the scanning lens 2105d and the return mirror 2106d. In this manner, when light is irradiated on the photosensitive drum 2030d by the light beam, a light spot is formed. This light spot moves in the longitudinal direction of the photosensitive drum 2030d when the polygon mirror 2104 rotates. That is, the light spot scans the photosensitive drum 2030d based on the rotation of the polygon mirror 2104.

  The direction in which the light spot moves is the main scanning direction. Therefore, the direction in which the photosensitive drum 2030d rotates is the sub-scanning direction.

  Each folding mirror is arranged at a position where the optical path length from the polygon mirror 2104 to each photosensitive drum is the same. Further, the folding mirrors are arranged such that the respective incident positions and incident angles of the respective light beams on the respective photosensitive drums are all the same.

  The optical system disposed on the optical path between the polygon mirror 2104 and each photosensitive drum is called a scanning optical system or the like. In this example, the scanning optical system of the K station is a scanning lens 2105a, a return mirror 2106a, and the like. The scanning optical system of the C station includes a scanning lens 2105b, folding mirrors 2106b and 2108b, and the like. Further, the scanning optical system of the M station includes a scanning lens 2105c, folding mirrors 2106c and 2108c, and the like. Furthermore, the scanning optical system of the Y station includes a scanning lens 2105d and a return mirror 2106d. In each scanning optical system, the scanning lens may be a plurality of lenses.

  In the configuration shown in FIG. 1, a direction tangential to the direction in which the photosensitive drum 2030 and the developing rollers 2033a, 2033b, 2033c, and 2033d rotate (hereinafter, referred to as a "first direction"), that is, around the Y axis. The tangential direction is the X-axis direction. The developing rollers 2033 a, 2033 b, 2033 c, and 2033 d have a so-called electromagnetic brush or the like, and rotate around the Y axis to make toner adhere to the photosensitive drum 2030, and come into contact with the photosensitive drum 2030. Note that a direction orthogonal to the first direction is referred to as a “second direction” in the following description.

<Example of hardware configuration>
FIG. 9 is a block diagram illustrating an example of a hardware configuration of the image forming apparatus according to the embodiment of the present disclosure. For example, the color printer 2000 includes a controller 2001, a first plotter control device 2002, a second plotter control device 2003, a memory 2004, a CPU (Central Processing Unit) 2005, and a third plotter control device 2006.

  First, a higher-level device is connected to the color printer 2000 via a network, wire, or wireless. Then, the higher-level device transmits a command for performing image formation, that is, a print request to the color printer 2000 based on a user operation or the like. When a print request is made, image data indicating an image to be formed by the color printer 2000 is sent from a higher-level device to a controller 2001 of the color printer 2000.

  The controller 2001 is, for example, an electronic circuit board on which a CPU and the like are mounted. For example, the controller 2001 performs image processing such as gradation processing such as dither processing and processing for converting image data sent from a host device into a bitmap format. Note that a device or the like that performs so-called image development may be connected to the subsequent stage of the controller 2001.

  The first plotter control device 2002, the second plotter control device 2003, and the third plotter control device 2006 include, for example, an application specific integrated circuit (ASIC), a PLD (Programmable Graphic Array) such as an FPGA (Field-Programmable Gate Array), or the like. And the like. Note that part of the processing performed by the first plotter control device 2002 may be executed by firmware or the like.

  The first plotter control device 2002 is a device for adding a pattern or performing image processing such as trimming. For example, the added pattern is a pattern for preventing forgery, a test pattern, a pattern for adjustment, or the like. The pattern for adjustment is, for example, a pattern for density adjustment, a pattern for color misregistration correction, or a pattern for blade entrainment avoidance. In the image processing, skew correction or the like may be performed. In addition, the first plotter control device 2002 performs a noise removal process, a pixel count process, a process of measuring the data capacity of image data, a process of converting 8-bit data into 10-bit data, and a process of converting parallel data into serial data. The conversion process is performed.

  The second plotter control device 2003 and the third plotter control device 2006 respectively perform, for example, similar processing. In the illustrated configuration, each light source is used to form one color image. For example, the light source 2200a is used to form an image of the color “K” among the colors “K”, “C”, “M”, and “Y”. The light source 2200b is used to form an image of the color “M” among the colors “K”, “C”, “M”, and “Y”. Further, the light source 2200c is used to form an image of the color “C” among the colors “K”, “C”, “M”, and “Y”. Furthermore, the light source 2200d is used to form an image of the color “Y” among the colors “K”, “C”, “M”, and “Y”. In the illustrated configuration, the second plotter control device 2003 and the third plotter control device 2006 respectively control the light sources for two colors. Note that the combination of colors does not have to be the combination shown. Therefore, the second plotter control device 2003 and the third plotter control device 2006 have a control device such as a driver for controlling the light source.

  Hereinafter, a case where the second plotter control device 2003 controls the light source 2200a to form an image of the color “K” will be described as an example. In the color printer, parameters for each color may be set in advance, and different processing may be performed for each color based on the parameters and the like.

  First, the second plotter control device 2003 receives image data (hereinafter, referred to as “first image data”) from the first plotter control device 2002. For example, the second plotter control device 2003 receives the first image data using an LVDS (Low voltage differential signaling) signal or the like. When the first plotter control device 2002 in the preceding stage performs a process of converting 8-bit data into 10-bit data, the second plotter control device 2003 performs inverse conversion, that is, converts 10-bit data into 8-bit data. The conversion process is performed. Then, the second plotter control device 2003 converts the first image data into a data format that matches the light emission resolution of the light source 2200a.

  For example, the light source 2200a is a laser array of VCSEL (Vertical Cavity Surface Emitting LASER, vertical cavity surface emitting laser). When the light source 2200a is a VCSEL, the light emission resolution can be as high as 2400 dpi (dots per inch) in the main scanning direction and 4800 dpi in the sub scanning direction.

  For example, when the first image data has a resolution of 2400 dpi and the light emission resolution is 4800 dpi, the second plotter control device 2003 performs a so-called double-density process or the like on the first image data, and outputs the first image data. Image data (hereinafter, referred to as “second image data”) obtained by converting the data into high resolution is generated. The conversion to a higher resolution is realized by, for example, LUT (Look Up Table) data or the like input in advance. Alternatively, the conversion to a higher resolution may be a conversion such as converting the data of each pixel (hereinafter referred to as “first pixel”) of the first image data into two pixels.

  Then, the second plotter control device 2003 converts the first image data to generate second image data. The details of the conversion procedure will be described later. Next, the second plotter control device 2003 controls the light source 2200a based on the second image data to form an image.

<Example of overall processing>
FIG. 10 is a flowchart illustrating an example of an overall process performed by the image forming apparatus according to the embodiment of the present disclosure. For example, a color printer forms an image by an image forming method as illustrated. In the following example, the resolution of the first image data in the column direction (Y direction, main scanning direction) is 2400 dpi, and the second image data is 4800 dpi.

<Example of setting specific data (step S01)>
In step S01, the color printer sets specific data. The specific data is, for example, data indicating a pattern detected by pattern matching when pattern matching is performed. For example, the specific data is the following data.

  FIG. 11 is a diagram illustrating an example of the specific data according to the embodiment of the present invention. As illustrated, the specific data is, for example, the four data illustrated in FIGS. 11A to 11D. In the illustrated example, each specific data is data of 6 pixels of 2400 dpi. In the illustrated example, each pixel is 1-bit data. Specifically, when the pixel indicates “0”, the pixel turns off the light source, that is, the toner is not attached to the portion corresponding to the pixel, so that the portion corresponding to the pixel is white (used for image formation). Paper to be printed is white). On the other hand, when the pixel indicates “1”, the pixel turns on the light source, that is, the portion corresponding to the pixel is black because the toner of “K” is attached to the portion corresponding to the pixel. Indicates that Note that which of “0” and “1” is black may be set in a color printer in advance. The specific data is not limited to the data of six pixels, and may be set based on, for example, the resolution of the first image data or the thickness of the target edge. That is, the specific data may be a number other than 6 pixels.

  Specifically, when the specific data as shown in FIG. 11A is set, the color printer can specify the following pixels, for example.

  FIG. 12 is a diagram (part 1) illustrating an example of a pixel specified based on the specified data according to the embodiment of the present invention. For example, an example will be described in which the first image data has a plurality of first pixels PX1 as illustrated. Specifically, it is assumed that a part of the first image data includes a pixel that forms an image of the vertical line LN1 as illustrated. In this example, the pattern indicated by the specific data shown in FIG. 11A and the pattern of six pixels in the second to seventh columns in the second row shown in the first pixel PX1 shown in FIG. Hereinafter, this will be referred to as “first specific pattern PT1”). As shown in the drawing, the first specific pattern PT1 is a pattern in which, in the right direction of the drawing, first two pixels indicating “0” continue, and then four pixels indicating “1” continue. That is, in the specific data shown in FIG. 11A and the first specific pattern PT1, both the numbers of pixels of “0” and “1” and the positions of “0” and “1” match. As described above, when the specific data is set, a pixel serving as a boundary (hereinafter, referred to as a “first target pixel”) can be specified when an image is formed on the vertical line LN1.

  For example, as shown in the example of the first specific pattern PT1, when forming the vertical line LN1 in the example of the first specific pattern PT1, the first target pixel is a pixel serving as a boundary between a pixel to be turned on and a pixel to be turned off (hereinafter, “left”). Edge pixel LPX ”). That is, the left edge pixel LPX is a left edge portion of the so-called vertical line LN1. In addition, the first target pixel is, for example, a pixel indicating “1” and a pixel that is “0” is an adjacent pixel as illustrated.

  When the specific data shown in FIG. 11A is set as described above, the color printer can specify the first target pixel as shown in FIG. 12 from the first pixel. Hereinafter, by using the specific data shown in FIGS. 11B to 11D, the color printer can similarly specify the first target pixel.

  Similarly, when the specific data as shown in FIG. 11B is set, the color printer can specify the following pixels, for example.

  FIG. 13 is a diagram (part 2) illustrating an example of a pixel specified based on the specified data according to an embodiment of the present invention. For example, an example will be described in which the first image data has a plurality of first pixels PX1 as illustrated. Specifically, it is assumed that a part of the first image data includes a pixel that forms an image of the vertical line LN2 as illustrated. In this example, the pattern indicated by the specific data shown in FIG. 11B and the pattern of six pixels in the sixth column to the eleventh column in the second row shown in the first pixel PX1 shown in FIG. Hereinafter, this will be referred to as “second specific pattern PT2”). As shown in the figure, the second specific pattern PT2 is a pattern in which, in the rightward direction in the figure, first four pixels indicating “1” continue, and then two pixels indicating “0” continue. That is, in the specific data shown in FIG. 11B and the second specific pattern PT2, both the numbers of the pixels “0” and “1” and the positions of “0” and “1” match. As described above, when the specific data is set, the first target pixel can be specified when the image is formed on the vertical line LN2.

  For example, in the example of the second specific pattern PT2, when forming the image of the vertical line LN2 in the example of the second specific pattern PT2, the first target pixel is a pixel serving as a boundary between a pixel to be turned on and a pixel to be turned off (hereinafter, “right Edge pixel RPX ”). That is, the right edge pixel RPX is a right edge portion of the so-called vertical line LN2. In addition, the first target pixel is, for example, a pixel indicating “1” and a pixel that is “0” is an adjacent pixel as illustrated.

  As described above, when the specific data shown in FIG. 11B is set, the color printer can specify the first target pixel as shown in FIG. 13 from the first pixel.

  Similarly, when the specific data as shown in FIG. 11C is set, the color printer can specify the following pixels, for example.

  FIG. 14 is a diagram (part 3) illustrating an example of a pixel specified based on the specified data according to the embodiment of the present invention. For example, an example will be described in which the first image data has a plurality of first pixels PX1 as illustrated. Specifically, it is assumed that a part of the first image data includes a pixel for forming an image of the horizontal line LN3 as illustrated. In this example, the pattern indicated by the specific data shown in FIG. 11C and the pattern of six pixels in the second to seventh rows in the fourth column shown in the first column PX1 shown in FIG. Hereinafter, this will be referred to as “third specific pattern PT3”). As shown in the figure, the third specific pattern PT3 is a pattern in which, in the downward direction of the figure, first two pixels indicating “0” continue, and then four pixels indicating “1” continue. That is, in the specific data shown in FIG. 11C and the third specific pattern PT3, both the numbers of pixels “0” and “1” and the positions of “0” and “1” match. As described above, when the specific data is set, the first target pixel can be specified when the horizontal line LN3 is image-formed.

  For example, as shown in the example of the third specific pattern PT3, when forming the horizontal line LN3 in the example of the third specific pattern PT3, the first target pixel is a pixel that is a boundary between a pixel to be turned on and a pixel to be turned off (hereinafter, “upper”). Edge pixel UPX ”). That is, the upper edge pixel UPX is a so-called upper edge portion of the horizontal line LN3. In addition, the first target pixel is, for example, a pixel indicating “1” and a pixel that is “0” is an adjacent pixel as illustrated.

  As described above, when the specific data shown in FIG. 11C is set, the color printer can specify the first target pixel as shown in FIG. 14 from the first pixel.

  Similarly, when the specific data as shown in FIG. 11D is set, the color printer can specify the following pixels, for example.

  FIG. 15 is a diagram (part 4) illustrating an example of a pixel specified based on the specified data according to an embodiment of the present invention. For example, an example will be described in which the first image data has a plurality of first pixels PX1 as illustrated. Specifically, it is assumed that a part of the first image data includes a pixel for forming an image of the horizontal line LN4 as illustrated. In this example, the pattern indicated by the specific data illustrated in FIG. 11D and the pattern of six pixels in the fourth to ninth rows in the illustrated fourth column, for example, among the first pixels PX1 illustrated in FIG. Hereinafter, this is referred to as “fourth specific pattern PT4”). As shown in the drawing, the fourth specific pattern PT4 is a pattern in which, in the downward direction of the figure, first, four pixels indicating “1” continue, and then two pixels indicating “0” continue. That is, in the specific data shown in FIG. 11D and the fourth specific pattern PT4, both the numbers of pixels of “0” and “1” and the positions of “0” and “1” match. As described above, when the specific data is set, the first target pixel can be specified when the horizontal line LN4 is formed as an image.

  For example, in the example of the fourth specific pattern PT4, when forming the image of the horizontal line LN4 in the example of the fourth specific pattern PT4, the first target pixel is a pixel that is a boundary between a pixel to be turned on and a pixel to be turned off (hereinafter, “lower”). Edge pixel DPX ”). That is, the lower edge pixel DPX is a lower edge portion of a so-called horizontal line LN4. In addition, the first target pixel is, for example, a pixel indicating “1” and a pixel that is “0” is an adjacent pixel as illustrated.

  Thus, when the specific data shown in FIG. 11D is set, the color printer can specify the first target pixel as shown in FIG. 15 from the first pixel.

  The specific data is not limited to the four patterns shown in FIG. For example, specific data may be further set in the color printer. For example, specific data indicating a pattern with the number of pixels other than six pixels, specific data having a different ratio of “0” and “1” from the pattern illustrated in FIG. 11, or the like may be further set.

<Setting Example of First Pixel Number (Step S02)>
Returning to FIG. 10, in step S02, in the first direction, the color printer converts the number of pixels to be turned on to the number of pixels to be turned off in the subsequent conversion (step S07 described later) (hereinafter, referred to as “first pixel number”). )).

<Setting Example of Second Pixel Number (Step S03)>
In step S03, in the second direction, the color printer sets the number of pixels (hereinafter, referred to as "second pixel number") to be converted into pixels to be turned off in a subsequent conversion (step S07 described later). .

  A detailed description of the first pixel number and the second pixel number will be described later. Further, the first pixel number and the second pixel number are separately and independently set. Note that the order in which the first pixel number and the second pixel number are set is not limited to the order shown in FIG. That is, the first pixel number and the second pixel number may be set to the second pixel number simultaneously or first, and then the first pixel number may be set.

<Example of receiving print instruction (step S04)>
Returning to FIG. 10, in step S04, the color printer accepts a print instruction. For example, in the configuration shown in FIG. 1, command data indicating printing instructions, image data, and the like are transmitted from a higher-level device to the color printer. As described above, when command data and the like are transmitted to the color printer, the color printer accepts a print instruction. Then, when receiving the print instruction, the color printer starts image processing on the transmitted image data. In the configuration shown in FIG. 1, the color printer first performs image processing by the controller 2001 (FIG. 1).

<Example of Tag Data Generation and Image Processing (Step S05)>
In step S05, the color printer uses the controller 2001 to generate tag data and perform image processing. Note that the tag data is data indicating an attribute of each pixel included in the image data. Specifically, first, it is assumed that the attribute of each pixel is classified into, for example, one of attributes of “image”, “text”, and “graphic”. This attribute depends on what kind of image is input to the image data so that each pixel of the image data forms an image by a user operation. For example, “text” is an attribute indicating that a pixel is a character or a line. More specifically, in the image data, when the user inputs a character or a line to form an image, the pixel is classified into a “text” attribute. On the other hand, when the user inputs a picture or the like to form an image, pixels are classified into attributes such as “image”.

  Hereinafter, in the subsequent processing, an example will be described in which a character or a line, that is, a pixel having an attribute of “text” is targeted. In this example, the tag data is 1-bit data. Specifically, when the pixel has the attribute of “text”, the tag data is “1”. On the other hand, when the pixel has the attribute other than “text”, the tag data is “0”. ".

  In step S05, the color printer performs image processing by the controller 2001 and the first plotter control device 2002 (FIG. 9) to generate first image data. Then, the color printer transmits the generated first image data to the second plotter control device 2003 (FIG. 9) or the like.

<Example of receiving first image data and tag data (step S06)>
In step S06, the color printer receives the first image data and the tag data. For example, the first image data and the tag data are received as follows.

  FIG. 16 is a timing chart illustrating an example of reception of the first image data and the tag data according to the embodiment of the present invention. For example, the first image data and the tag data are received by a signal synchronized with the clock signal CLK. In the illustrated example, the first image data DIMG1 and the tag data DTG are each 1-bit data, and one clock of the clock signal CLK is data of one pixel.

  Specifically, for example, at the first timing T1, the first image data DIMG1 is “0”, so that the first image data DIMG1 indicates that the light source is turned off. On the other hand, at the second timing T2, since the first image data DIMG1 is “1”, the first image data DIMG1 indicates that the light source is turned on. At the second timing T2, the tag data DTG is "1", which indicates that the first image data DIMG1 at the second timing T2 has the attribute of "text". As described above, when the first image data DIMG1 is “1”, the tag data DTG indicates the attribute of the pixel.

  Therefore, even if the first image data DIMG1 is “1”, the tag data DTG is “0” if the first image data DIMG1 has an attribute other than “text”. For example, the third timing T3 is an example in which the tag data DTG becomes "0" even if the first image data DIMG1 is "1". In this case, the image is a picture or the like.

<Example of converting first image data to second image data (step S07)>
Returning to FIG. 10, in step S07, the color printer performs conversion from the first image data to the second image data. Specifically, first, the color printer specifies the first target pixel as shown in FIGS. 12 to 15 by pattern matching or the like based on the specific data. Then, the color printer converts the specified first target pixel and the other first pixels, for example, as follows.

  FIG. 17 is a diagram illustrating a first example of conversion according to an embodiment of the present invention. Hereinafter, an example in which each first pixel included in the first specific pattern PT1 illustrated in FIG. 12 is converted into a pixel of the second image data (hereinafter, referred to as a “second pixel”) as illustrated.

  In this example, the first specific pattern PT1 is converted into a first conversion pattern PT1A. Each first pixel included in the first specific pattern PT1 is converted into four second pixels. As shown in the figure, the first target pixel specified in advance (in this example, the left edge pixel LPX) is four second pixels (hereinafter, referred to as “second target pixel LPX2”) corresponding to the first target pixel. .) Are all converted to “0”.

  Further, when the left edge pixel LPX has the attribute of “text” based on the tag data, the conversion as illustrated is performed. In other words, if the left edge pixel LPX has the attribute that the tag data is “1” as in the second timing T2 shown in FIG. 16, the left edge pixel LPX is changed by the color printer as shown in FIG. It is converted to the target pixel LPX2. On the other hand, if the left edge pixel LPX has an attribute other than “text”, that is, if the tag data has an attribute of “0” as in the third timing T3 shown in FIG. Like the second pixels other than the two target pixels LPX2, the four first pixels are converted to reflect the value indicated by the first pixel. That is, the four second pixels after the conversion are all converted to show the same value.

  In the case of the conversion as shown, an image is formed such that a line or a character becomes thinner by two pixels in the column direction at 4800 dpi. “2 pixels” is the number of pixels set by the second number of pixels. That is, FIG. 17 is an example in which “2” is set in advance as the second pixel number.

  Then, the color printer converts the first image data so as to have a high resolution as shown in FIG. That is, when the so-called double-density processing is performed on the first image data, the second image data is generated. The color printer can form a thin line or character image by performing a so-called thinning process in the conversion for generating the second image data.

  Similarly, as shown in FIG. 13, the specified first pixel is converted as follows, for example.

  FIG. 18 is a diagram illustrating a second example of conversion according to an embodiment of the present invention. Hereinafter, an example in which each first pixel included in the second specific pattern PT2 illustrated in FIG. 13 is converted into a second pixel as illustrated will be described.

  In this example, the second specific pattern PT2 is converted into a second converted pattern PT2A. As in FIG. 17, each first pixel included in the second specific pattern PT2 is converted into four second pixels. As illustrated, the first target pixel (the right edge pixel RPX in this example) specified in advance is four second pixels (hereinafter, referred to as “second target pixel RPX2”) corresponding to the first target pixel. .) Are all converted to “0”. Note that what is converted to be the second target pixel RPX2 is the right edge pixel RPX whose tag data is “1”.

  In the case of the conversion as shown, an image is formed such that a line or a character becomes thinner by two pixels in the column direction at 4800 dpi. “2 pixels” is the number of pixels set by the second number of pixels. That is, FIG. 18 is an example in which “2” is set in advance as the second pixel number.

  Then, the color printer converts the first image data to have a high resolution, as in FIG. That is, when the so-called double-density processing is performed on the first image data, the second image data is generated. The color printer can form a thin line or character image by performing a so-called thinning process in the conversion for generating the second image data.

  Similarly, as shown in FIG. 14, the specified first pixel is converted as follows, for example.

  FIG. 19 is a diagram illustrating a third example of conversion according to an embodiment of the present invention. Hereinafter, an example will be described in which each first pixel included in the third specific pattern PT3 illustrated in FIG. 14 is converted into a second pixel as illustrated.

  In this example, the third specific pattern PT3 is converted into a third converted pattern PT3A. As in FIG. 17, each first pixel included in the third specific pattern PT3 is converted into four second pixels. As illustrated, the first target pixel (in this example, the upper edge pixel UPX) specified in advance is four second pixels (hereinafter, referred to as “second target pixel UPX2”) corresponding to the first target pixel. .), Two pixels adjacent to “1” are converted to be “1”. On the other hand, the other second target pixels UPX2 are converted to “0”. That is, the pixels included in the second target pixel are converted so that half of the four pixels are “0” and the other half are “1”. Note that the upper edge pixel UPX whose tag data is “1” is converted to be the second target pixel UPX2.

  With the conversion shown in the figure, an image is formed such that a line or a character becomes thinner by one pixel in the row direction at 4800 dpi. “One pixel” is the number of pixels set by the first number of pixels. That is, FIG. 19 is an example in which “1” is set in advance to the first pixel number.

  Then, the color printer converts the first image data to have a high resolution, as in FIG. That is, when the so-called double-density processing is performed on the first image data, the second image data is generated. The color printer can form a thin line or character image by performing a so-called thinning process in the conversion for generating the second image data.

  Similarly, as shown in FIG. 15, the specified first pixel is converted as follows, for example.

  FIG. 20 is a diagram illustrating a third example of conversion according to an embodiment of the present invention. Hereinafter, an example in which each first pixel included in the fourth specific pattern PT4 illustrated in FIG. 15 is converted to a second pixel as illustrated will be described.

  In this example, the fourth specific pattern PT4 is converted into a fourth converted pattern PT4A. As in FIG. 17, each first pixel included in the fourth specific pattern PT4 is converted into four second pixels. As shown in the figure, the first target pixel specified in advance (in this example, the lower edge pixel DPX) is four second pixels (hereinafter, referred to as “second target pixel DPX2”) corresponding to the first target pixel. .), Two pixels adjacent to “1” are converted to be “1”. On the other hand, the other second target pixels DPX2 are converted to be “0”. That is, the pixels included in the second target pixel are converted so that half of the four pixels are “0” and the other half are “1”. Note that the lower edge pixel DPX whose tag data is "1" is converted to be the second target pixel DPX2, as in FIG.

  With the conversion shown in the figure, an image is formed such that a line or a character becomes thinner by one pixel in the row direction at 4800 dpi. “One pixel” is the number of pixels set by the first number of pixels. That is, FIG. 20 is an example in which “1” is set in advance to the first pixel number.

  Then, the color printer converts the first image data to have a high resolution, as in FIG. That is, when the so-called double-density processing is performed on the first image data, the second image data is generated. The color printer can form a thin line or character image by performing a so-called thinning process in the conversion for generating the second image data.

  In the conversion, the thinning process is not limited to the process of thinning one pixel or two pixels as shown in FIGS. That is, the thinning process may be a process of thinning two pixels or more as long as the thinning process is set to a value set in advance and is thinned by two pixels or more.

  As shown in FIGS. 17 and 18 and FIGS. 19 and 20, the number of pixels converted in the row direction, that is, the first pixel number, and the number of pixels converted in the column direction, that is, the second pixel number Means that different values can be set separately. Specifically, in the above example, while FIGS. 17 and 18, that is, the second pixel number is set to “2”, FIGS. 19 and 20, that is, the first pixel number is “1”. And different values are set independently and separately. Each set value is set, for example, in a register or the like. Therefore, as shown in FIGS. 17 and 18 and FIGS. 19 and 20, the image forming apparatus can perform different thinning processing in the row direction and the column direction. Note that the first pixel number and the second pixel number may have the same value.

  As described above, if different values can be separately set for the first pixel number and the second pixel number, it is possible to perform thinning processing for different pixel numbers in the row direction and the column direction. The forming apparatus can adjust the ratio between the length and the width, that is, the so-called aspect ratio.

  Also, as shown in FIGS. 17 to 20, the first pixel number and the second pixel number are such that the column direction, that is, the second pixel number, has a larger value than the row direction, that is, the first pixel number. It is desirable to be set to.

  The developing rollers 2033a, 2033b, 2033c, and 2033d (FIG. 1) may cause toner to adhere to the photoconductor, and then chip away when leaving the photoconductor. Therefore, assuming that the direction in which the developing rollers 2033a, 2033b, 2033c, and 2033d rotate is the first direction, in the first direction, lines and the like may become thin due to lack of toner. On the other hand, in the second direction, chipping of the toner by the developing rollers 2033a, 2033b, 2033c, and 2033d is unlikely to occur.

  Therefore, even if the image data has the same width in the first direction and the second direction, a line having the same width may not be formed. Therefore, it is desirable that the second pixel number be set to a value larger than the first pixel number. In this way, the thinning process is performed in the second direction so as to be thinner than the first direction, as shown in FIGS. Therefore, even if toner is missing in the first direction by the developing rollers 2033a, 2033b, 2033c, and 2033d, if the respective values of the first pixel number and the second pixel number are set, the image forming apparatus is substantially the same. Can be formed as an image.

  Note that a phenomenon in which toner is lacked by the developing rollers 2033a, 2033b, 2033c, and 2033d may be referred to as “scan benge” or the like.

  The conversion such as the double density processing is, for example, the following processing.

  FIG. 21 is a diagram illustrating a first example of the double density process performed by the image forming apparatus according to the embodiment of the present disclosure. For example, in the case where the first image data has a resolution of 2400 dpi and one pixel is 1-bit data indicating whether the light source is turned on or off, FIGS. The conversion shown is performed. The illustrated example is an example in which second image data having a resolution of 4800 dpi and one pixel being 1-bit data is generated. This example is an example of conversion performed when there is no first target pixel, that is, when the attribute is “text” and there is no edge pixel as shown in FIGS.

  The conversion may use image data related to another resolution. For example, the first image data may have a resolution of 600 dpi or less.

  Further, the first image data may be data in which one pixel has 2 bits or more. For example, when a pixel included in the first image data, that is, when the first pixel is 2-bit data, the conversion may be performed as follows.

  FIG. 22 is a diagram illustrating a second example of the double density process performed by the image forming apparatus according to the embodiment of the present disclosure. The example shown is a case where the first pixel is 2-bit data and has any value from “0” to “3”. For the first pixel, “0” indicates that image formation is not performed, and the larger the numerical value, the higher the density of image formation. Also, in this example, it is assumed that the color printer can be set in advance so as to perform the conversion of any of the combinations shown in FIGS.

  The illustrated example is an example in which so-called upward alignment is performed. Specifically, the upper alignment is a form in which, when the first pixel is “1” or “2”, the second pixels that become “1” are concentrated and arranged at the top in the drawing. Further, FIG. 22A shows a format in which the second pixels that become “1” are concentrated on the left side in the figure. FIGS. 22B and 22C show a format in which the second pixels that are “1” are arranged at the center in the drawing. FIG. 22D shows a format in which the second pixels that become “1” are concentrated and arranged on the right side in the figure.

  Alternatively, when the first pixel is 2-bit data, the conversion may be the following processing.

  FIG. 23 is a diagram illustrating a third example of the double density process performed by the image forming apparatus according to the embodiment of the present invention. The conversion shown is a case where the first pixel is 2-bit data and has a value from “0” to “3”, as in FIG. Further, in this example, it is assumed that the color printer can be set in advance so as to perform the conversion of any of the combinations shown in FIGS. 23 (A) to 23 (F).

  As compared with FIG. 22, the conversion shown in FIG. 23 is the same when the first pixel is “1” or “3”. The example shown in FIG. 23 has a format in which a pixel “1” is shifted to the center in the row direction.

  Further, the first pixel may be 2-bit or more data (hereinafter, referred to as “multi-bit data”). When the first pixel is multi-bit data, the arrangement of the lit pixels in the second pixel is determined based on the value indicated by the first pixel. For example, when the first pixel is multi-bit data of 2-bit data, the conversion may be the following processing.

  FIG. 24 is a diagram illustrating a fourth example of the double density process performed by the image forming apparatus according to the embodiment of the present invention. The conversion shown is a case where the first pixel is 2-bit data and has a value from “0” to “3”, as in FIG. Also, in this example, it is assumed that the color printer can be set in advance so as to perform the conversion of any of the combinations shown in FIGS.

  As compared with FIG. 22, the conversion shown in FIG. 23 is the same when the first pixel is “1” or “3”. The example shown in FIG. 23 is an example in which a so-called lowering is performed.

  Specifically, the bottom alignment is a form in which, when the first pixel is “1” or “2”, the second pixels that become “1” are concentrated in the lower part of the drawing. Further, FIG. 24A shows a format in which the second pixels that are “1” are arranged intensively to the left in the figure. FIGS. 24B and 24C show a format in which the second pixels that are “1” are arranged at the center in the drawing. FIG. 24D illustrates a format in which the second pixels that are “1” are concentrated on the right side in the drawing.

  Furthermore, when the first pixel is 2-bit data, the conversion may be the following processing.

  FIG. 25 is a diagram illustrating a fifth example of the double density process performed by the image forming apparatus according to the embodiment of the present disclosure. The conversion shown is a case where the first pixel is 2-bit data and has a value from “0” to “3”, as in FIG. In this example, it is assumed that the color printer can be set in advance so as to perform the conversion of either the combination of FIG. 25A or FIG. 25B.

  In comparison with FIGS. 22 to 24, the conversion shown in FIG. 25 is an example in which “justification” is not performed and “1” is relatively uniformly arranged. On the other hand, when compared with FIG. 22, the conversion shown in FIG. 25 is the same when the first pixel is “1” or “3”.

  FIG. 26 is a diagram illustrating a comparative example in the double density processing by the image forming apparatus. For example, a case where an image is formed as shown in FIG. In the example shown in FIG. 26A, the light source is controlled to turn on based on the image data at the eleventh timing T11, as shown in FIG. 26B. Then, as shown in FIG. 26B, there is a case where the next pixel, that is, image data which is controlled to turn off at the twelfth timing T12. In such a case, depending on the response speed of the light source, switching on and off of the light source may not be in time, as shown in FIG. Therefore, the image data shown in FIG. 26A is converted as follows.

  FIG. 27 is a diagram illustrating an example of a processing result of the double density processing performed by the image forming apparatus according to the embodiment of the present disclosure. For example, the image data illustrated in FIG. 27A is image data generated by the conversion illustrated in FIG. 23E or FIG. Compared to the case shown in FIG. 26, FIG. 27B is different in that there is no control to switch between lighting and extinguishing at the twelfth timing T12 and the thirteenth timing T13, and the lighting is maintained. In this case, as shown in FIG. 26C, it is possible to reduce the occurrence of an unintended image being formed due to a failure to respond to the switching on and off of the light source in time.

  Further, both the first pixel and the second pixel may be multi-bit data. For example, when the first pixel and the second pixel are 4-bit data each indicating a hexadecimal value of “0” to “F”, the following conversion may be performed.

  FIG. 28 is a diagram illustrating a first example of conversion of multi-bit data according to an embodiment of the present invention. FIG. 28 shows an example in which each pixel is multi-bit data in FIG. It is assumed that each pixel indicates a density at which an image is formed by a numerical value. In this example, it is assumed that the density becomes white when the value becomes “0”, and becomes closer to black as the numerical value becomes larger. Specifically, the density is a value indicating a duty ratio or a lighting time of a control signal for lighting the light source. The control signal is, for example, a PWM (Pulse Width Modulation) signal.

  As illustrated, the difference from FIG. 17 is that the pixels used are multi-bit data. First, as illustrated, the processing is the same as that in FIG. 17 except for the case where the left edge pixel LPX is the left edge pixel LPX and the left edge pixel LPX has the “text” attribute.

  In this example, the first specific pattern PT1 is converted into a first conversion pattern PT1A. Each first pixel included in the first specific pattern PT1 is converted into four second pixels by the double density process. As shown in the figure, the first target pixel specified in advance (in this example, the left edge pixel LPX) is four second pixels (hereinafter, referred to as “second target pixel LPX3”) corresponding to the first target pixel. .), The pixel adjacent to “F” is converted to “4”. On the other hand, the other second target pixels LPX3 are converted to be “0”. That is, the pixels included in the second target pixel are converted so that half of the four pixels are “4” and the other half are “0”.

  On the other hand, the second pixels other than the second target pixel LPX3 are converted to have the same value as the first pixel. Specifically, if the first pixel is “0”, all of the second pixels other than the second target pixel LPX3 become “0” by reflecting the value indicated by the first pixel. Is converted. On the other hand, if the first pixel is “F”, the second pixels other than the second target pixel LPX2 are all converted to “F” by reflecting the value indicated by the first pixel. You.

  Further, when the left edge pixel LPX has the attribute of “text” based on the tag data, the conversion as illustrated is performed. That is, when the left edge pixel LPX has the attribute of which the tag data is “1” as in the second timing T2 shown in FIG. 16, the left edge pixel LPX is changed by the color printer as shown in FIG. It is converted to the target pixel LPX3. On the other hand, if the left edge pixel LPX has an attribute other than “text”, that is, if the tag data has an attribute of “0” as in the third timing T3 shown in FIG. Like the second pixels other than the two target pixels LPX3, the four first pixels are converted to reflect the value indicated by the first pixel. That is, the four second pixels after the conversion are all converted to show the same value.

  In the case of the conversion as shown in the figure, an image is formed such that a line or a character becomes thinner in the column direction at 4800 dpi. Further, the color printer converts the first image data so as to have a high resolution as shown in FIG. That is, when the so-called double-density processing is performed on the first image data, the second image data is generated. The color printer can form a thin line or character image by performing a so-called thinning process in the conversion for generating the second image data.

  Further, the conversion is not limited to the conversion in which half of the four pixels included in the second target pixel are set to “4” and the other half are set to “0”. The conversion may be, for example, a conversion to another value as follows.

  FIG. 29 is a diagram illustrating a second example of conversion of multi-bit data according to an embodiment of the present invention. Compared with FIG. 28, the difference is that the pixel converted to be “4” in FIG. 28 is converted to “8” in FIG. That is, in FIG. 29, of the four second pixels corresponding to the first target pixel (hereinafter, referred to as “second target pixel LPX4”), the pixel adjacent to “F” is converted to “8”.

  FIG. 30 is a diagram illustrating a third example of conversion of multi-bit data according to an embodiment of the present invention. Compared with FIG. 28, the difference is that the pixel converted to be “4” in FIG. 28 is converted to “C” in FIG. That is, in FIG. 30, among the four second pixels corresponding to the first target pixel (hereinafter, referred to as “second target pixel LPX5”), the pixel adjacent to “F” is converted to “C”.

  When the second pixel is multi-bit data, like the second target pixel LPX4 shown in FIG. 29 and the second target pixel LPX5 shown in FIG. 30, the conversion is performed so that the density becomes a preset density value. Done.

  The pattern matching performed in the conversion is performed, for example, as follows.

  FIG. 31 is a diagram illustrating an example of pattern matching performed by the image forming apparatus according to an embodiment of the present invention. For example, a color printer uses a 9 × 9 image matrix as shown, centering on a pixel (hereinafter referred to as a “pixel of interest FPX”) that is determined to be a first target pixel by pattern matching. Perform pattern matching.

  Note that the size of the image matrix is not limited to 9 × 9. For example, the size of the image matrix may be larger than 9 × 9, such as 11 × 11. By using a large size image matrix, the color printer can increase the number of variations for specifying the first target pixel. Further, by using a large-sized image matrix, the color printer can improve the detection accuracy for specifying the first target pixel. On the other hand, for example, the size of the image matrix may be smaller than 9 × 9, such as 7 × 7. When an image matrix having a small size is used, the color printer can reduce the circuit scale related to the image matrix.

  Specifically, in the pattern matching, for example, the color printer determines whether or not the target pixel FPX and the periphery have the same arrangement as the specific data shown in FIG. 11 and the like. Hereinafter, an example of pattern matching using specific data shown in FIG. In this case, in the pattern matching, the color printer first determines whether or not the target pixel FPX is “0”. If the target pixel FPX is not “0”, the color printer determines that the pixel is not a pixel of the specific data shown in FIG. Then, based on the specific data shown in FIG. 11A, the pixel adjacent to the left of the target pixel FPX is “0”, and the four pixels adjacent to the right of the target pixel FPX are all “1”. It is determined whether or not there is. Subsequently, when the pixel adjacent to the left of the target pixel FPX is “0” and all the four pixels adjacent to the right of the target pixel FPX are “1”, the color printer performs the operation shown in FIG. Are determined to be pixels of the specific data shown in FIG. Next, based on the tag data, the color printer determines whether or not the target pixel FPX has the “text” attribute.

  If the pixel of the specific data shown in FIG. 11A and the pixel of interest has the attribute of “text”, the color printer performs the conversion as shown in FIG. It is determined that the pixel is the first target pixel to be performed.

  In the pattern matching, a priority may be set. Specifically, first, priorities are set in advance for a plurality of patterns detected by pattern matching. The image forming apparatus detects patterns in descending order of priority by pattern matching. Then, when a pattern that corresponds to a plurality of patterns is detected, it may be determined that the pattern corresponds to a higher priority pattern.

  When pattern matching is performed by an electronic circuit or the like, it is often impossible to execute a plurality of pattern matchings at one time. Thus, by setting the priority in this way, the image forming apparatus can perform a plurality of pattern matchings using an electronic circuit or the like.

  In the pattern matching, it may be determined based on the color of the target pixel FPX whether or not the target is to be thinned. For example, it may be set in advance so that a black pixel is specified. Black characters or lines can often maintain image quality even when thinned. Therefore, pixels of black characters or lines may be specified by pattern matching.

<Example of image formation based on second image data (step S08)>
Returning to FIG. 10, in step S08, the color printer forms an image based on the second image data. That is, the color printer forms an image on a recording medium based on the image data generated by the conversion.

<Embodiment for performing smoothing process>
Further, the image forming apparatus performs a process of smoothing a step (hereinafter, simply referred to as a “step”) that becomes an edge in an image in both the row direction and the column direction and becomes a corner in an image, that is, a so-called smoothing process. Is also good. The smoothing process may be a smoothing process or a process for leveling a step. Hereinafter, an example of the smoothing process will be described.

  FIG. 32 is a diagram illustrating a first example of smoothing processing and thinning processing by the image forming apparatus according to an embodiment of the present invention. First, the step LV is in a state as shown in FIG. 32A, for example. Hereinafter, the step LV shown in FIG. 32A will be described as an example. Note that, in this example, as in FIG. 17 and the like, FIG. 32A is an image of 2400 dpi, and is converted into an image of 4800 dpi shown in FIG. 32B. Also, in this example, as in FIG. 17 and the like, when the pixel is “0”, the light source is turned off, while when the pixel is “1”, the light source is turned on.

  The smoothing process and the thinning process for FIG. 32A are, for example, processes for changing the state shown in FIG. 32A to the state shown in FIG. Specifically, first, the image forming apparatus detects a pixel serving as a step LV by pattern matching or the like.

  Next, when the level difference LV is detected, the image forming apparatus performs a smoothing process and a thinning process. Then, when the smoothing process and the thinning process are performed, a part of the predetermined pixel indicating “1” included in the step LV in FIG. 32A becomes “0” as shown in FIG. Pixel. That is, when the smoothing process and the thinning process are performed, the region where the light source is turned on is reduced, and the step LV is leveled.

  The step is not limited to the state shown in FIG. For example, the direction of the step or the width of the step (height difference) may be different. Further, data indicating a level difference used for pattern matching is input to the image forming apparatus in advance.

  Further, the step LV may have the following pattern.

  FIG. 33 is a diagram illustrating a second example of the smoothing process and the thinning process performed by the image forming apparatus according to the embodiment of the present invention. Hereinafter, as in FIGS. 17 to 20, an example will be described in which the first pixel number is set to “1” and the second pixel number is set to “2”.

  As in FIG. 32, first, the image forming apparatus detects a pixel serving as a step LV by pattern matching or the like.

  Next, when the level difference LV is detected, the image forming apparatus performs a smoothing process and a thinning process. Then, when the smoothing process and the thinning process are performed, a part of the predetermined pixel indicating “1” included in the step LV in FIG. 33A becomes “0” as shown in FIG. Pixel. That is, when the smoothing process and the thinning process are performed, the region where the light source is turned on is reduced, and the step LV is leveled.

  As described above, in the illustrated example, also in the smoothing process, the image forming apparatus converts the pixels in the column direction such that the light source is turned off by the number of pixels set to the second number of pixels. Further, the image forming apparatus converts the pixels in the row direction such that the light source is turned off by the number of pixels set to the first number of pixels. By doing so, the image forming apparatus can adjust the aspect ratio in the process for the step, that is, in the smoothing process and the like, and can improve the image quality.

<Functional configuration example>
FIG. 34 is a diagram illustrating an example of a functional configuration of the image forming apparatus according to an embodiment of the present invention. As illustrated, the color printer 2000 includes, for example, a receiving unit 2000F1, a specific data setting unit 2000F2, a data receiving unit 2000F3, a converting unit 2000F4, an image forming unit 2000F5, a first setting unit 2000F6, a second setting unit 2000F7, and the like. .

  The receiving unit 2000F1 receives data indicating a print instruction, image data, and the like from the higher-level device illustrated in FIG. For example, the receiving unit 2000F1 is realized by the controller 2001 (FIG. 9), the first plotter control device 2002 (FIG. 9), the CPU 2005 (FIG. 9), and the like.

  The data receiving unit 2000F3 includes a first image data DIMG1 having a plurality of first pixels indicating either of turning on / off a light source or a density at which an image is formed, and a tag indicating an attribute of each of the first pixels. And data DTG. For example, the data receiving unit 2000F3 is realized by the second plotter control device 2003 (FIG. 9), the third plotter control device 2006 (FIG. 9), and the like.

  The specific data setting unit 2000F2 sets specific data DS that can specify a first target pixel to be changed among the first pixels. For example, the specific data setting unit 2000F2 is realized by the CPU 2005 (FIG. 9).

  The first setting unit 2000F6 sets a first pixel number PN1 to be turned off in the first direction. For example, the first setting unit 2000F6 is realized by the CPU 2005.

  The second setting unit 2000F7 sets a second pixel number PN2 to be turned off in a second direction orthogonal to the first direction. For example, the second setting unit 2000F7 is realized by the CPU 2005.

  The conversion unit 2000F4 converts the first image data DIMG1 into the second image data DIMG2 having a higher resolution than the first image data DIMG1, and converts the first image data DIMG1 into the second image data DIMG2 based on the specific data DS and the tag data DTG. Of the two pixels, a second target pixel corresponding to the first target pixel is specified, and a part or all of the second target pixel is a pixel for turning off the light source based on the first pixel number PN1 and the second pixel number PN2. To generate the second image data DIMG2. For example, the conversion unit 2000F4 is realized by the second plotter control device 2003 (FIG. 9), the third plotter control device 2006 (FIG. 9), and the like.

  The image forming unit 2000F5 controls the light source based on the second image data DIMG2 to form an image. For example, the image forming unit 2000F5 is realized by the second plotter control device 2003 (FIG. 9) and the third plotter control device 2006 (FIG. 9).

  The color printer 2000 first receives a print instruction, image data, and the like using the receiving unit 2000F1. On the other hand, the specific data DS is preset in the color printer 2000 by the specific data setting unit 2000F2. Similarly, the first setting unit 2000F6 and the second setting unit 2000F7 preset the first pixel number PN1 and the second pixel number PN2.

  When the receiving unit 2000F1 receives image data indicating an image to be printed, the color printer 2000 performs image processing and the like to generate first image data DIMG1. On the other hand, the color printer 2000 generates tag data DTG indicating the attribute of each first pixel included in the first image data DIMG1.

  The first image data DIMG1 and tag data DTG generated in this way are received by the data receiving unit 2000F3, for example, as shown in FIG. Next, the color printer 2000 converts the first image data DIMG1 into high-resolution second image data DIMG2 by performing double-density processing or the like by the conversion unit 2000F4. In the conversion, the color printer 2000 determines whether there is a second target pixel corresponding to the first target pixel among the second pixels included in the second image data DIMG2 based on the specific data DS and the tag data DTG. to decide. Specifically, first, the color printer 2000 determines whether or not the first target pixel has a character or line attribute based on the tag data DTG. Further, the color printer 2000 performs pattern matching based on the specific data DS, for example, as illustrated in FIG. 31, and determines whether or not the pixel is a first target pixel such as an edge portion.

  In this manner, based on the specific data DS and the tag data DTG, when the color printer 2000 determines that the attribute is a character or a line and that it is the first target pixel, as shown in FIG. Performs a process to make thin characters and the like thin. Note that the first pixel number PN1 and the second pixel number PN2 are set separately. Therefore, the color printer 2000 can have different finenesses in the first direction and the second direction. In this manner, the color printer 2000 can form an image of characters, lines, and the like thinly.

  In image formation, particularly in an electrophotographic system using toner, a developing roller having an electromagnetic brush is often used. Therefore, in a direction in which the developing roller rotates, a phenomenon that the toner is chipped by the developing roller may occur. Therefore, in the image forming apparatus according to the embodiment of the present invention, the amount of thinning in each of the first direction and the second direction is separately set according to the first pixel number and the second pixel number. With this configuration, the image forming apparatus can change the number of pixels when converting the light source into the pixels for turning off the light source in the first direction and the second direction. Thus, the image forming apparatus can adjust the aspect ratio.

  Therefore, the image forming apparatus can adjust the aspect ratio of a line or a character on which an image is formed. Thus, the image forming apparatus can improve the image quality.

  The image forming apparatus can determine whether each pixel is data indicating a character or a line by using the tag data. If pixels other than characters or lines, for example, pixels such as pictures are converted as shown in FIG. 17 or the like, the color tone or the like often changes. Therefore, using the tag data, the image forming apparatus desirably selects a pixel indicating a character or a line and performs conversion as shown in FIG. With this configuration, the image forming apparatus can improve the image quality of an image such as a pattern other than a character or a line. It is preferable that the tag data is 1-bit data indicating whether or not the data indicates a character or a line. When the data is 1-bit data, the image forming apparatus can reduce the data capacity of the tag data as compared with the case where the tag data is multi-bit data.

  Further, it is desirable that the conversion be performed after the control of the light source. Specifically, in the configuration shown in FIG. 9, it is desirable that the conversion is performed by the second plotter control device, the third plotter control device, or the like. When the conversion is performed, double density processing and the like are performed. Therefore, after conversion, the data transfer amount often increases. Therefore, it is desirable that the processing be performed at a subsequent stage as in the second plotter control device and the third plotter control device. By doing so, the image forming apparatus can reduce the data transfer amount before the conversion. On the other hand, it is desirable that the processing for thinning characters or lines is performed at a high resolution. When the processing is performed at a high resolution, the amount by which the character or the line is reduced can be specified in detail. For example, at a resolution of 4800 dpi, the amount by which a character or line is thinned in units of 5 microns can be specified. Note that the resolution of the second image data is preferably at least twice the resolution of the first image data. In this manner, the image forming apparatus can form a higher definition image.

  Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the specific embodiments, and various modifications may be made within the scope of the present invention described in the appended claims. Or it can be changed.

2000 Color printer DIMG1 First image data DIMG2 Second image data DS Specific data DTG Tag data

JP 2015-177242 A

Claims (15)

An image forming apparatus that performs image formation using a light source,
Receives first image data having a plurality of first pixels indicating whether the light source is turned on or off, or a density at which an image is formed, and tag data indicating respective attributes of the first pixels. A data receiving unit;
A specific data setting unit that sets specific data that can specify a first target pixel to be changed among the first pixels;
A first setting unit that sets a first number of pixels to be turned off in a first direction;
A second setting unit that sets a second number of pixels to be turned off in a second direction orthogonal to the first direction;
In the conversion of the first image data into second image data having a higher resolution than the first image data, based on the specific data and the tag data, among the second pixels included in the second image data, A second target pixel corresponding to a first target pixel is specified, and a part or all of the second target pixel is set as a pixel for turning off the light source based on the first pixel number and the second pixel number. A conversion unit for generating two image data;
An image forming apparatus comprising: an image forming unit configured to control the light source based on the second image data to form an image. The conversion unit may set pixels having different numbers of pixels in the first direction and the second direction as pixels for turning off the light source based on the first number of pixels and the second number of pixels which are separately set. Item 2. The image forming apparatus according to Item 1. The image forming unit has a developing roller,
The first direction is tangential to a direction in which the developing roller rotates,
3. The image forming apparatus according to claim 1, wherein the second pixel number is set to a value larger than the first pixel number. 4.   4. The image forming apparatus according to claim 1, wherein a resolution of the second image data is at least twice a resolution of the first image data. 5.   The image forming apparatus according to claim 1, wherein the conversion unit specifies the first target pixel by pattern matching. The specific data is data indicating a plurality of patterns in the pattern matching,
The image forming apparatus according to claim 5, wherein a priority is set for the pattern.   The image forming apparatus according to claim 1, wherein the conversion unit specifies the black first target pixel.   The image forming apparatus according to claim 1, wherein the first target pixel is a character or an edge of a line.   The image forming apparatus according to claim 1, wherein the tag data is 1-bit data indicating whether the first pixel is a character or a line.   10. The image forming apparatus according to claim 1, wherein the conversion unit sets one or more pixels for turning on the light source to one or more pixels for turning off the light source to make characters or lines thin. 11.   The image forming apparatus according to claim 10, wherein the conversion unit sets a pixel for turning on the light source to a pixel for turning off the light at a resolution of the second image data.   The image forming apparatus according to claim 1, wherein the first pixel and the second pixel are 1-bit data indicating whether to turn on or off the light source.   The image forming apparatus according to claim 1, wherein the first pixel and the second pixel are multi-bit data indicating the density. When the first image data includes a pixel serving as a step,
Performing a smoothing process to smooth out the step, and generating the second image data by setting a pixel related to the step to a pixel for turning off the light source based on the first pixel number and the second pixel number The image forming apparatus according to claim 1, wherein: An image forming method performed by an image forming apparatus that forms an image using a light source,
The image forming apparatus displays first image data including a plurality of first pixels indicating whether the light source is turned on or off, or a density at which an image is formed, and an attribute of each of the first pixels. A data receiving procedure for receiving the tag data,
A specific data setting procedure in which the image forming apparatus sets specific data capable of specifying a first target pixel to be changed among the first pixels;
A first setting procedure in which the image forming apparatus sets a first number of pixels to be turned off in a first direction;
A second setting procedure in which the image forming apparatus sets a second number of pixels to be turned off in a second direction orthogonal to the first direction;
The image forming apparatus converts the first image data into second image data having a higher resolution than the first image data, based on the specific data and the tag data; Of the two pixels, a second target pixel corresponding to the first target pixel is specified, and a part or all of the second target pixel is turned off based on the first pixel number and the second pixel number. A conversion procedure for generating the second image data with the pixels to be
An image forming procedure in which the image forming apparatus controls the light source to form an image based on the second image data.