JP2007152731A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an image with a required degree of resolution or degree of gradation without restricting the maximum value of the degree of resolution or the degree of gradation of image data to powers of two. <P>SOLUTION: When the maximum value of the degree of resolution or the degree of gradation of the image data obtained is "12", a PLL part 8 forms a multiplied clock made by 6-multiplying the frequency of a pixel clock, and outputs it to a PWM generating part 9. The PWM generating part 9 synchronizes the standing-up or standing-down of the multiplied clock inputted from the PLL part 8, and forms pulse signals (PWM values=1, 2, ... 12) having 12 kinds of different pulse widths. For example, when the degree of resolution or the degree of gradation of one pixel included in the image data obtained is "1", the PWM generating part 9 outputs a pulse signal of the PWM value=1. In addition, when the degree of resolution or the degree of gradation of one pixel included in the image data obtained is "2", the PWM generating part 9 outputs a pulse signal of the PWM value=2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generates a plurality of types of pulse signals having different pulse widths based on acquired image data, and adjusts the amount of light applied to the photoconductor according to the pulse width of the generated pulse signals to form an image. The present invention relates to a forming apparatus.

  An image forming apparatus such as a digital copying machine having a scanner function, a printer function, a facsimile function, or the like, or a printer apparatus is based on image data read by an image reading apparatus or image data acquired from an external personal computer or the like. A pulse signal with a modulated pulse width is generated, and an image is formed by forming an image of laser light modulated according to the pulse width of the generated pulse signal on the surface of the photosensitive drum.

  For example, a plurality of pattern signals having different waveform shapes are generated, and each of the plurality of pattern signals is compared with the multi-value image data by a plurality of modulation means to perform pulse width modulation. An image forming apparatus capable of obtaining a high-quality reproduced image without reducing the resolution by selecting one of the modulation signals output from the plurality of modulation means based on the characteristics of the multi-value image data Has been proposed (see Patent Document 1).

Further, when the set value set according to the desired exposure amount is equal to or smaller than a predetermined value, the light output is modulated so as to gradually increase with time for a period according to the exposure amount, and the set value Is greater than a predetermined value, the light output is gradually increased over time for a period corresponding to the exposure amount, and when the light output reaches a predetermined value, the light output is held at the predetermined value, and the light output is determined according to the exposure amount. There has been proposed a semiconductor laser modulation device that can obtain a stable exposure amount by holding and modulating only for a period (see Patent Document 2).
JP-A-2-67154 JP-A-4-83661

  The modulation method of laser light used in the devices of Patent Documents 1 and 2 is a pulse signal whose pulse width is modulated by a pulse generation circuit according to the resolution or gradation of each pixel of an image formed on a photoconductor. And output to the semiconductor laser drive circuit. The semiconductor laser drive circuit adjusts the amount of laser light emitted from the semiconductor laser according to the pulse width of the input pulse signal, and synchronizes with the pixel clock for forming each pixel on the photoconductor in the main scanning direction. An image is formed on the photosensitive member by irradiating with laser light.

  In order to increase the image forming speed (printing speed), that is, the scanning speed of the laser beam onto the photosensitive member, it is necessary to increase the frequency of the pixel clock. The pulse generation circuit uses a frequency higher than the frequency of the pixel clock in order to modulate the pulse width of the generated pulse signal within one cycle of the pixel clock. Therefore, the operation limit when the image forming speed is increased is determined by the operation frequency limit of the pulse generation circuit.

  Since the maximum value of image resolution or gradation is generally expressed as a power of 2, the degree of modulation of the pulse width of the pulse signal (the number of types of pulse signals having different pulse widths) is also a power of 2 ( For example, since numerical values limited to 8, 16, 32,... Are used, the pulse width of the pulse signal can be modulated only by discrete values. In particular, when the power of 2 is large, this discrete width becomes large. Therefore, when the operation limit of the pulse generation circuit has not been reached, the maximum value of the resolution or gradation of the image can be kept low, and vice versa. The problem that the image resolution or gradation cannot be increased in accordance with the operation limit of the pulse generation circuit, such as when the maximum value of image resolution or gradation cannot be increased due to the operation limit of the pulse generation circuit. was there.

  The present invention has been made in view of such circumstances, and generation means for generating a pulse signal in which the number of types of pulse signals having different pulse widths is an integer value other than a power of 2, and an acquired image When the maximum value of the resolution or gradation of data is represented by an integer value other than a power of 2, the pulse width of the pulse signal generated by the generating unit is controlled based on each pixel data included in the image data It is an object of the present invention to provide an image forming apparatus capable of forming an image with a desired resolution or gradation without being limited to a power of 2.

  Another object of the present invention is to provide a multiplication means for multiplying a reference clock for irradiating the photoconductor with a light amount corresponding to each pixel of an image to be formed, based on the multiplied clock. An image forming apparatus capable of increasing the resolution or gradation of an image to be formed in accordance with the limit of the operating frequency of the multiplied clock by generating a pulse signal in which the number of types of the pulse signal is determined. There is to do.

  Another object of the present invention includes a plurality of multiplying means for multiplying the reference clock to different values, and a selecting means for selecting the multiplying means, and based on the multiplied clock multiplied by the selected multiplying means, An object of the present invention is to provide an image forming apparatus capable of setting a resolution or gradation of an image to be formed to a value desired by a user by generating a pulse signal in which the number of types of the pulse signal is determined.

  Another object of the present invention is to convert a resolution or gradation having a maximum value represented by a power of 2 into a resolution or gradation having a maximum value represented by an integer value other than a power of 2. When the maximum value of the resolution or gradation of the acquired image data is represented by a power of 2, by multiplying the reference clock according to the resolution or gradation converted by the conversion means, An object of the present invention is to provide an image forming apparatus capable of forming an image with a desired resolution or gradation even when the discrete width of the maximum value of the resolution or gradation of the acquired image is large.

  Another object of the present invention is to convert a resolution or gradation expressed by a power of 2 to a different resolution or gradation expressed by an integer value other than a power of 2. Conversion means, and a selection means for selecting the conversion means, and when the maximum value of the resolution or gradation of the acquired image data is expressed by a power of 2, conversion is performed by the conversion means selected by the selection means By multiplying the reference clock according to the resolution or gradation, the resolution or gradation of the image to be formed can be increased even when the maximum discrete width of the resolution or gradation of the image to be acquired is large. An object of the present invention is to provide an image forming apparatus which can be set to a value desired by a user.

  The image forming apparatus according to the present invention generates a plurality of types of pulse signals having different pulse widths based on the acquired image data, and adjusts the amount of light applied to the photoconductor according to the pulse width of the generated pulse signals. In an image forming apparatus for forming an image, generation means for generating a pulse signal in which the number of types of pulse signals having different pulse widths is an integer value other than a power of 2, and the resolution or gradation of the acquired image data Control means for controlling the pulse width of the pulse signal generated by the generating means based on each pixel data included in the image data when the maximum value is represented by an integer value other than a power of 2; It is characterized by.

  An image forming apparatus according to the present invention includes a multiplying unit that multiplies a reference clock for irradiating a photoconductor with a light amount corresponding to each pixel of an image to be formed, and the generating unit is the multiplying unit. A pulse signal in which the number of types of the pulse signal is determined is generated based on the multiplied clock.

  The image forming apparatus according to the present invention includes a plurality of multiplication means for multiplying the reference clock to different values, and a selection means for selecting the multiplication means, and the generation means is the multiplication means selected by the selection means. A pulse signal having a predetermined number of types of the pulse signal is generated based on the multiplied clock multiplied by 1.

  An image forming apparatus according to the present invention includes a conversion unit for converting a resolution or gradation expressed by a power of 2 to a resolution or gradation expressed by an integer value other than a power of 2. And the multiplication means multiplies the reference clock according to the resolution or gradation converted by the conversion means when the maximum resolution or gradation of the acquired image data is expressed by a power of 2. It is characterized by being done.

  The image forming apparatus according to the present invention has a plurality of resolutions or gradations for converting a resolution or gradation expressed by a power of 2 to a different resolution or gradation expressed by an integer value other than a power of 2. A conversion means; and a selection means for selecting the conversion means. The multiplication means is selected by the selection means when the maximum value of the resolution or gradation of the acquired image data is expressed by a power of 2. The reference clock is multiplied in accordance with the resolution or gradation converted by the converting means.

  In the present invention, the generation unit generates a pulse signal in which the number of types of pulse signals having different pulse widths is an integer value other than a power of 2. When the maximum value of the resolution or gradation of the acquired image data is represented by an integer value other than a power of 2, the control means is generated by the generation means based on each pixel data included in the image data. Controls the pulse width of the pulse signal. For example, when the maximum value of the resolution or gradation of the acquired image data is “14” which is not a power of 2, the generation unit determines that the pulse width is based on each pixel data (for example, resolution or gradation). A pulse signal composed of 14 different pulses is generated. Thus, a pulse signal having a pulse with a different number of pulse widths that is not limited to a power of 2 is generated according to the resolution or gradation of each pixel data included in the acquired image data.

  In the present invention, the multiplication means multiplies a reference clock (pixel clock) for irradiating the photoconductor with a light amount corresponding to each pixel of the formed image for each pixel. The generation means generates a pulse signal in which the number of types of the pulse signal is determined based on the multiplied clock. For example, when the multiplying unit multiplies the reference clock by 7, the generating unit generates 14 pulse signals having different pulse widths in synchronization with the rising or falling timing of the multiplied clock. Thus, the generation means generates a pulse signal having a different pulse width in accordance with the limit of the operation frequency even when the frequency of the multiplied clock is close to the limit of the operation, and increases the resolution or gradation of the image to be formed. To do.

  In the present invention, the selection means selects one multiplication means from a plurality of multiplication means for multiplying the reference clock to different values. The generating means generates a pulse signal in which the number of types of the pulse signal is determined based on the multiplied clock multiplied by the selected multiplying means. For example, when a plurality of multiplying means for multiplying the reference clock by 6 times, 7 times, 9 times,... Are provided in advance, and the user forms an image with a desired resolution or gradation, a plurality of selecting means may By selecting one of the multiplying means, a pulse signal having a different pulse width is generated based on the multiplied clock multiplied by the selected multiplying means.

  In the present invention, when the maximum value of the resolution or gradation of the acquired image data is represented by a power of 2, the conversion means maximizes the resolution or gradation represented by the power of 2. The value is converted into a resolution or gradation expressed by an integer value other than a power of 2. The multiplication means multiplies the reference clock in accordance with the resolution or gradation expressed by an integer value other than the converted power of 2.

  In the present invention, the selection means converts the resolution or gradation expressed by a power of 2 to a different resolution or gradation expressed by an integer value other than a power of 2. One is selected from a plurality of conversion means. The multiplication unit multiplies the reference clock according to the resolution or gradation converted by the selected conversion unit when the maximum resolution or gradation of the acquired image data is expressed by a power of 2. To do. For example, when the maximum value of the resolution or gradation of the acquired image data is “8”, which is a power of 2, the selected conversion means sets the resolution or gradation of the maximum value “8” to the maximum value. Is converted to a resolution or gradation of “14”, the multiplication means multiplies the reference clock by 7 so that the generation means generates pulse signals having 14 different pulse widths.

  In the present invention, the generation means for generating a pulse signal in which the number of types of pulse signals having different pulse widths is an integer value other than a power of 2, and the maximum value of the resolution or gradation of the acquired image data are When represented by an integer value other than a power of 2, the control means for controlling the pulse width of the pulse signal generated by the generating means based on each pixel data included in the image data, Without being limited to a power, an image can be formed with a desired resolution or gradation.

  In the present invention, the pulse generator includes a multiplying unit that multiplies a reference clock for irradiating the photoconductor with a light amount corresponding to each pixel of an image to be formed, and the pulse is based on the multiplied clock. By generating a pulse signal in which the number of signal types is determined, the resolution or gradation of an image to be formed can be increased in accordance with the limit of the operating frequency of the multiplied clock.

  In the present invention, the pulse signal includes a plurality of multiplying means for multiplying the reference clock to different values, and a selecting means for selecting the multiplying means, and the pulse signal based on the multiplied clock multiplied by the selected multiplying means. By generating a pulse signal in which the number of types is determined, for example, the resolution or gradation of an image to be formed can be set to a value desired by the user.

  In the present invention, there is provided conversion means for converting the resolution or gradation expressed by a power of 2 into a resolution or gradation expressed by an integer value other than the power of 2. When the maximum value of the resolution or gradation of the acquired image data is represented by a power of 2, the reference clock is multiplied by the resolution or gradation converted by the conversion unit to obtain the image to be acquired. Even when the discrete width of the maximum value of resolution or gradation is large, an image can be formed with a desired resolution or gradation.

  In the present invention, a plurality of conversion means for converting a resolution or gradation expressed by a power of 2 into a different resolution or gradation expressed by an integer value other than a power of 2. And a selecting means for selecting the converting means, and the resolution converted by the converting means selected by the selecting means when the resolution of the acquired image data or the maximum gradation value is expressed by a power of 2 Alternatively, by multiplying the reference clock according to the gradation, the resolution or gradation of the image to be formed can be determined by the user even if the resolution of the image to be acquired or the discrete width of the maximum gradation is large. The value can be

Embodiment 1
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments. FIG. 1 is a schematic diagram showing a configuration of a main part of an image forming apparatus according to the present invention. The image forming apparatus includes an optical writing unit 100, a process control unit, which will be described later, and the like, and performs image formation by an electrophotographic method. The optical writing unit 100 includes a semiconductor laser 1, a polygon mirror 2, a motor 3, an fθ lens 4, a laser light detection sensor 5, a mirror 6, and the like.

  The laser light L emitted from the semiconductor laser 1 is reflected by the polygon mirror 2 that is rotationally driven by the motor 3, and the laser light L reflected by the polygon mirror 2 is scanned on the photoreceptor 50 by raster scanning. An image is formed on the photoreceptor 50 through the fθ lens 4 that corrects the optical path difference. As a result, the image forming apparatus forms an electrostatic latent image on the photoconductor 50 and forms an image on the recording paper by electrophotography. The laser beam L reflected from the poringon mirror 2 is reflected by the mirror 6, and the reflected laser beam is detected by the laser beam detection sensor 5, and the start of scanning on the photosensitive member 50 is detected.

  FIG. 2 is a block diagram showing the configuration of the process control unit 200. The process control unit 200 includes a PLL (Phase Locked Loop) unit 8, a PWM (Pulse Width Modulation) generation unit 9, a driver 10, a control unit 11, and the like.

  The PLL unit 8 generates a multiplied clock obtained by multiplying the frequency of the pixel clock based on a pixel clock output from a crystal oscillator (not shown), and outputs the generated multiplied clock to the PWM generating unit 9. The pixel clock is for ensuring the timing at which the dot light per pixel is irradiated when the laser beam L is scanned on the photoconductor 50. That is, an electrostatic latent image for each pixel is formed on the photoconductor 50 in synchronization with the pixel clock. The PLL unit 8 is configured to generate a plurality of multiplied clocks in advance, and can select an output multiplied clock based on a control signal output from the control unit 11. As the multiplying clock, for example, the pixel clock frequency is multiplied by an integer value other than a power of 2, such as 6, 7, 9, and so on.

  The PWM generator 9 acquires image data output from an external personal computer (not shown) connected via a communication line or the like. In this case, the maximum value of the resolution or gradation of the acquired image data is represented by an integer value other than a power of 2. For example, the maximum value of the resolution or gradation of the image data is “12”, “14”, “18”,. The PWM generation unit 9 generates a pulse signal that has been subjected to pulse width modulation based on a multiplied clock selected in accordance with the maximum resolution or gradation of the acquired image data, and is included in the acquired image data. A pulse signal having a pulse width corresponding to the resolution or gradation of each pixel is generated and output to the driver 10.

  The driver 10 outputs a drive signal corresponding to the pulse width of the pulse signal input from the PWM generator 9 to the semiconductor laser 1. Thereby, the semiconductor laser 1 outputs dot light according to the pulse signal subjected to pulse width modulation.

  The control unit 11 includes a microcomputer and controls the entire process control unit 200. For example, when a desired resolution or gradation is selected in the operation unit 60 including various keys and switches that accept user operation instructions, based on an operation signal output from the operation unit 60 to the control unit 11, The control unit 11 outputs a control signal to the PLL unit 8 so as to output a predetermined multiplied clock.

  FIG. 3 is a timing chart showing an example of a pulse signal subjected to pulse width modulation. As shown in the figure, for example, when the maximum value of the resolution or gradation of the acquired image data is “12”, the PLL unit 8 generates a multiplied clock obtained by multiplying the frequency of the pixel clock by 6 to generate PWM. Output to the generator 9. The PWM generator 9 synchronizes with the rising or falling timing of the multiplied clock input from the PLL unit 8 and outputs pulse signals having 12 different pulse widths (PWM values = 1, 2,..., 12). Generate.

  For example, when the resolution or gradation of one pixel included in the acquired image data is “1”, the PWM generator 9 outputs a pulse signal with a PWM value = 1. In addition, when the resolution or gradation of one pixel included in the acquired image data is “2”, the PWM generator 9 outputs a pulse signal with a PWM value = 2. Similarly, when the resolution or gradation of one pixel included in the acquired image data is “12”, the PWM generator 9 outputs a pulse signal with a PWM value = 12. Laser light (dot light whose lighting time is controlled) is irradiated on the photosensitive member 50 in accordance with the resolution or gradation level of each pixel during one period of the pixel clock. The

  FIG. 4 is a timing chart showing another example of a pulse signal subjected to pulse width modulation. As shown in the figure, for example, when the resolution or the maximum gradation value of the acquired image data is “14”, the PLL unit 8 generates a multiplied clock obtained by multiplying the frequency of the pixel clock by 7 to generate PWM. Output to the generator 9. The PWM generator 9 generates pulse signals (PWM values = 1, 2,..., 14) having 14 different pulse widths in synchronization with the rising or falling timing of the multiplied clock input from the PLL unit 8. Generate.

  For example, when the resolution or gradation of one pixel included in the acquired image data is “1”, the PWM generator 9 outputs a pulse signal with a PWM value = 1. In addition, when the resolution or gradation of one pixel included in the acquired image data is “2”, the PWM generator 9 outputs a pulse signal with a PWM value = 2. Similarly, when the resolution or gradation of one pixel included in the acquired image data is “14”, the PWM generator 9 outputs a pulse signal with a PWM value = 14. Laser light (dot light whose lighting time is controlled) is irradiated on the photosensitive member 50 in accordance with the resolution or gradation level of each pixel during one period of the pixel clock. The

  Since the pulse signal (PWM value) generated by the PWM generator 9 is pulse width modulated in synchronization with the rising and falling timings of the multiplied clock, it is temporarily generated by the multiplied clock having a frequency higher than the frequency of the pixel clock. When the generation operation of the pulse signal is near the frequency limit, the resolution or gradation of the image can be increased to the limit of the circuit performance.

  FIG. 5 is an explanatory diagram showing the relationship between the resolution or gradation of the image and the characteristics of the photoreceptor. In the right half of the figure, the horizontal axis indicates the resolution or gradation of the image data, and the vertical axis indicates the PWM value (modulated pulse width) of the pulse signal, that is, the lighting time of the dot light per pixel. In the figure, the straight line indicated by □ represents the resolution or gradation of image data and the modulated pulse width (PWM value) when the maximum resolution or gradation is the cube of 2 (“8”). Represents a relationship. Further, the straight line indicated by ○ indicates that the resolution or gradation of image data and the modulated pulse width (PWM value) when the maximum value of resolution or gradation is “14” (an integer value other than a power of 2). Represents the relationship.

  When the operation limit of the PWM generator 9 is, for example, a multiplication clock of 7 times the pixel clock, when the pulse width modulation is performed based on the conventional power of 2, the maximum value of resolution or gradation is set to 2 4 The power ("16") cannot be set, and the cube of 2 ("8") is the limit, and the maximum resolution or gradation is limited to "8" or less. On the other hand, when an integer value other than a power of 2 is set as the maximum value of resolution or gradation as in the present invention, the maximum resolution or gradation is up to “14”, which is the limit of circuit performance. Can be increased.

  On the other hand, in the left half of the figure, the horizontal axis indicates the sensitivity of the photoconductor, and the vertical axis indicates the intensity of light per pixel irradiated on the photoconductor. The intensity of light on the vertical axis corresponds to the PWM value (modulated pulse width) of the pulse signal, that is, the lighting time of dot light per pixel. The curves in the figure show the characteristics of the photoconductor, and curves A, B, and C depend on the environmental conditions such as temperature or humidity around the apparatus, the difference in the material of the photoconductor, the use conditions or the deterioration status of the photoconductor. It changes as follows. By increasing the resolution or gradation of the image data, the characteristics of the photoconductor can be set more finely, and a desired image can be formed and an image with excellent reproducibility can be formed.

Embodiment 2
In the first embodiment described above, the maximum value of the resolution or gradation of the acquired image data is represented by an integer value other than a power of 2, but is represented by a power of 2. There may be. FIG. 6 is a block diagram illustrating a configuration of the process control unit 200 according to the second embodiment. The difference from the first embodiment is that a lookup table (LUT) 13 is provided.

  The LUT 13 converts the resolution or gradation expressed by a power of 2 into a resolution or gradation expressed by an integer value other than the power of a maximum value of 2. For example, the LUT 13 converts a value represented by a power of 2 such as 1, 2, 4, 8, 16 or the like into an integer value other than a power of 2, such as 6, 10, 12, 14, or the like.

  The reflected light reflected from the document image surface is collected by an optical lens and imaged on a CCD line sensor to be converted into an electrical signal. The LUT 13 converts image data based on the electrical signal converted by the CCD line sensor. Image data output from an image reading unit (not shown) to be acquired or an external personal computer connected via a communication line or the like is acquired. The LUT 13 converts the maximum resolution (for example, “8”) of the acquired image data into “12”, and outputs the converted image data to the PWM generator 9.

  The control unit 11 outputs a control signal to the PLL unit 8 and the LUT 13 based on the operation signal output from the operation unit 60 to the control unit 11, and controls so that a predetermined multiplied clock is output. The LUT 13 is selected. The operations of the PLL unit 8, the PWM generation unit 9, the driver 10 and the like are the same as those in the first embodiment, and thus description thereof is omitted.

  As described above, in the present invention, the image is not limited to a power of 2, and an image can be formed with a desired resolution or gradation. Further, the resolution or gradation of an image to be formed can be increased in accordance with the limit of the operating frequency of the multiplied clock. Further, the resolution or gradation of the image to be formed can be set to a value desired by the user. Further, even when the maximum width of the resolution or gradation of the acquired image is a large power such as a power of 2, an image can be formed with a desired resolution or gradation.

  In the above-described embodiment, the multiplication clock has been described with respect to the 6-fold multiplication and the 7-fold multiplication. However, the present invention is not limited to this, and a configuration using other numerical values may be used. Moreover, although the case where the maximum value of the resolution or the gradation is 12 and 14 has been described, the present invention is not limited to this, and may be an integer value other than a power of 2. Further, the value of resolution or gradation is an example, and is not limited to this.

  In the above-described embodiment, the semiconductor laser is used as a light source for irradiating the photosensitive member with light. However, the present invention is not limited to this, and an LED or the like may be used.

  In the above-described embodiment, the configuration in which the LUT is built in the image forming apparatus has been described. However, the present invention is not limited to this, and a configuration in which the LUT is provided in an external personal computer or the like may be used.

1 is a schematic diagram illustrating a configuration of a main part of an image forming apparatus according to the present invention. It is a block diagram which shows the structure of a process control part. It is a timing chart which shows the example of the pulse signal by which the pulse width modulation was carried out. It is a timing chart which shows the other example of the pulse signal by which the pulse width modulation was carried out. It is explanatory drawing which shows the relationship between the resolution or gradation of an image, and the characteristic of a photoreceptor. FIG. 6 is a block diagram illustrating a configuration of a process control unit according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser 2 Polygon mirror 3 Motor 4 f (theta) lens 5 Laser light detection sensor 6 Mirror 8 PLL part 9 PWM generation part 10 Driver 11 Control part 50 Photoconductor 60 Operation part 100 Writing unit 200 Process control part

Claims (5)

In the image forming apparatus that generates a plurality of types of pulse signals having different pulse widths based on the acquired image data, and adjusts the amount of light applied to the photoconductor according to the pulse width of the generated pulse signals to form an image.
Generating means for generating a pulse signal in which the number of types of pulse signals having different pulse widths is an integer value other than a power of 2, and
When the maximum value of the resolution or gradation of the acquired image data is represented by an integer value other than a power of 2, the pulse signal generated by the generating unit based on each pixel data included in the image data An image forming apparatus comprising: control means for controlling a pulse width. A multiplying unit for multiplying a reference clock for irradiating the photoconductor with a light amount corresponding to each pixel of an image to be formed;
The generating means includes
2. The image forming apparatus according to claim 1, wherein a pulse signal in which the number of types of the pulse signal is determined is generated based on the multiplied clock multiplied by the multiplying unit. A plurality of multiplication means for multiplying the reference clock to different values;
Selection means for selecting the multiplication means, and
The generating means includes
3. The pulse signal according to claim 2, wherein a pulse signal having a predetermined number of types of the pulse signal is generated based on the multiplied clock multiplied by the multiplying means selected by the selecting means. Image forming apparatus. A conversion means for converting the resolution or gradation expressed by a power of 2 to a resolution or gradation expressed by an integer value other than the power of 2.
The multiplication means is
When the maximum value of the resolution or gradation of the acquired image data is expressed by a power of 2, the reference clock is to be multiplied according to the resolution or gradation converted by the conversion means. The image forming apparatus according to claim 2. A plurality of conversion means for converting the resolution or gradation represented by a power of 2 to a different resolution or gradation represented by an integer value other than the power of 2.
Selection means for selecting the conversion means, and
The multiplication means is
When the maximum value of resolution or gradation of the acquired image data is expressed by a power of 2, the reference clock is multiplied according to the resolution or gradation converted by the conversion means selected by the selection means. The image forming apparatus according to claim 4, wherein the image forming apparatus is appropriately configured.

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