JP3574589B2 - Multi-beam printer device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multi-beam printer that prints image data by simultaneously scanning a plurality of laser beams with a phase difference.
[0002]
[Prior art]
In order to increase the speed of the laser beam printer, it is necessary to scan the laser beam at high speed in the main scanning direction and the sub-scanning direction. Specifically, the rotating polygon mirror is rotated at high speed in the main scanning direction, and the photoconductor is rotated at high speed in the sub-scanning direction.
However, the rotation speed of the rotary polygon mirror that deflects the laser beam (laser light) is near the limit. For this reason, instead of increasing the rotation speed of the rotary polygon mirror, a multi-beam method is adopted in which a plurality of laser beams are simultaneously scanned with a phase difference.
The reason why the plurality of laser beams have a phase difference is to secure a distance between the laser beams in order to eliminate the influence between the laser beams by arranging the laser light sources (arrays) in an inclined manner.
When a multi-valued image is printed by a laser beam printer, a pulse width modulation method is used in a system that is easily affected by the environment, such as electrophotography, from the viewpoint of image quality and stability.
[0003]
As a method of generating a multi-step pulse in the pulse width modulation method, for example, as described in JP-A-62-39972, a triangular wave generated in synchronization with image data and a D / A conversion output of the image data are used. An analog generation method to be compared and a digital method in which a high-speed clock having a frequency of 4 to 8 times the pixel clock is input and generated by logic processing such as frequency division as described in JP-A-5-6438. is there. There is a digital pulse width modulation method in which a plurality of delay elements (gates and the like) are connected in series and a predetermined number of delay elements are selected to perform pulse width modulation without using high-speed lock. A pulse width modulation method using a plurality of delay elements is suitable for a high-speed printer, and is widely used.
[0004]
As described above, a laser beam printer often employs a combination of a multi-beam system and a pulse width modulation system in order to perform high-speed printing.
[0005]
[Problems to be solved by the invention]
It is necessary to provide a pulse generator for generating a pulse having a width modulated for each laser beam. However, in a pulse width modulation method using a delay element such as a gate, variations in a pulse generation unit that generates a pulse having a multi-step pulse width, i.e., differences in component layout and wiring length during manufacturing, differences in environment, The generated pulse width differs between beams due to a variation factor such as variation in components used. Therefore, there is a problem that the light quantity varies due to the pulse width variation between the beams, and as a result, the size of the dots to be printed varies, so that the print quality deteriorates.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a purpose thereof is to correct a pulse width error (deviation) for each laser beam to print image data with high image quality. It is to provide a device.
[0007]
[Means for Solving the Problems]
The feature of the present invention is that a pulse is generated in synchronization with a plurality of pulse generators for pulse width modulation of image data, and a pulse width deviation between a pulse width of each pulse generator and a reference pulse width is obtained. The pulse width of each pulse generator is corrected so that the pulse width deviation of the pulse generator becomes zero.
[0008]
In the present invention, the pulse width correction of each pulse generation unit is performed by selecting the number of delay elements of the pulse width adjustment unit configured by connecting a plurality of delay elements in series.
[0009]
Note that the reference pulse in the present invention is desirably a pulse of one of the plurality of pulse generators, and one pulse generator is used to generate a pulse in synchronization with each pulse generator. It is desirable to share the pixel clock given to each of the pulse generators.
[0010]
According to the present invention, since the pulse width of each pulse width modulation device for setting the light amounts of a plurality of laser beams is corrected to be equal, the print dot size by each laser beam can be made equal, and the image data can be converted to high image quality. Can be printed.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 show one embodiment of the present invention.
[0012]
FIG. 2 illustrates the pulse width modulation device 10 and the laser printer 3 in FIG. 1 in detail, and shows an example of scanning with four laser beams.
[0013]
In FIG. 1, image data D1 created by a host computer (personal computer) 1 is input to a printer controller 2. The image data D1 is created by a user using input means (not shown) of the host computer 1. The image data D1 will be described as page description data indicating the content of the page to be recorded.
[0014]
The image data D1 output from the host computer 1 is transmitted to the printer controller 2 via a network (not shown) or the like, and is input to the raster image (RIP) developing device 9.
[0015]
The printer controller 2 includes a RIP expansion device 9, a correction data generation unit 5, a beam synchronization unit 30, a pulse width modulation device 10, a pulse width correction device 11, a pixel clock selection unit 4, a variation correction command generation unit 6, and a printer I / O. An F (interface) 12 is provided.
[0016]
The RIP developing device 9 develops, for each page, the image data D1 that is the page description data transmitted from the host computer 1, generates a raster image that is an array of two-dimensional image data, and generates a raster image that can express gradation. The value is output to the beam synchronization unit 30 as value image data D2.
[0017]
Upon receiving the variation correction command BC, the correction data generation unit 5 generates correction data D6 and outputs it to the beam synchronization unit 30.
[0018]
The beam synchronizer 30 converts the multi-valued image data D2 as multi-valued image data D3 (D3-1 to D-4) synchronized with the beam detection signals BD (BD-1 to BD-4) of the four laser beams. Output to the pulse width modulator 10.
[0019]
The pulse width modulation device 10 performs pulse width modulation of the image data D3 (D3-1 to D4), and applies the pulse to the print data D4 (D4-1 to D4-1) to the laser printer 3. As shown in FIG. 2, the pulse width modulation device 10 includes four pulse width modulation (PWM) pulse generators 303 to 306 equal to the number of laser beams.
[0020]
When given the variation correction command BC, the pulse width correction device 11 obtains the light amount correction data (pulse width correction amount) PC of each of the PWM pulse generation units 303 to 306 and adds it to the pulse width modulation device 10 as described later.
[0021]
Upon receiving the variation correction command BC, the pixel clock selection unit 4 selects one of the pixel clocks PCK1 to PCK4 input from the printer I / F 12, and sets the selected pixel clock SPCK as the selected pixel clock SPCK and the pulse synchronization unit 30 with the pulse synchronizer 30. Input to the modulation device 10.
[0022]
The variation correction command generation unit 6 outputs a variation correction command BC when the power of the apparatus is turned on and according to a variation correction command request signal BCREQ input from outside.
[0023]
The printer I / F 12 transmits a print request signal PREQ to the laser printer 3, and upon receiving the beam detection signal BD, separates each of the beam synchronization signals BD-1 to BD-4 from the beam detection signal BD, and further separates each beam synchronization signal. A pixel clock PCK synchronized with BD-1 to BD-4 is generated.
[0024]
As shown in FIG. 2, the laser printer 3 inputs the print data D4-1 to D4 modulated by the pulse width modulator 10 and supplies drive currents I1 to I4 to laser diodes (LD) 44 to 47.
[0025]
FIG. 3 shows an example detailed configuration diagram of the PWM pulse generation unit 303.
[0026]
In FIG. 3, the PWM pulse generation unit 303 includes a reference clock generation unit 213, a delay clock generation unit 201, a delay time measurement unit 202, a delay clock selection unit 203, a pulse generation unit 204, a pulse selection unit 205, a pulse width adjustment unit 420, It is composed of a fine clock generator 460.
[0027]
The reference clock generator 213 receives the pixel clock PCK-1 and generates a reference clock SCK.
[0028]
The delay clock generator 201 receives the reference clock SCK and generates a plurality of delay clocks DCK having different delay times.
[0029]
The delay time measuring unit 202 measures the delay time of the delay clock DCK periodically or irregularly, such as when the apparatus is started or immediately before the image forming process, by inputting the delay time measurement command signal MES.
[0030]
The delay clock selector 203 generates a selected delay clock SDCK depending on the measured delay time DLT from the delay clock DCK.
[0031]
The pulse generation unit 204 performs a logical operation of the reference clock SCK and the plurality of selection delay clocks SDCK to generate a plurality of pulses GPW.
[0032]
The pulse selection unit 205 receives the multi-valued image data D3-1 and selects one from a plurality of generated pulses GPW and a plurality of pulses including all white (all 0) and all black (all 1). Then, it outputs the print data APW modulated in the time axis direction (pulse width modulation).
[0033]
The pulse width adjustment unit 420 includes ten buffer gates (delay elements) 471 to 480 connected in series as shown in FIG. The pulse width adjustment unit 420 selects one of the outputs APW-1 to APW-10 of the delay elements 471 to 480 according to the light amount correction data PC-1, and increases or decreases the pulse width of the print data APW to generate the print data D4-1. I do. One delay time of the delay elements 471 to 480 is about 1 ns to 3 ns.
[0034]
FIG. 5 shows an example of a configuration diagram of the pulse width correction device 11.
[0035]
5, the pulse width correction device 11 includes a target value setting unit 20, a subtraction unit 21, and a light quantity correction data conversion unit 400.
[0036]
The target value setting unit 20 selects (sets) one of the print data D4-1 to D-4 input from each of the PWM pulse generation units 303 to 306 of the pulse width modulation device 10 as a reference pulse width, and performs target modulation. The value (reference pulse width modulation value) TPW is output to the subtraction unit 21 and the light quantity correction data conversion unit 400. In the present embodiment, a case will be described in which the largest one of the print data D4-1 to D4-4 is set as the target value, but the order of the pulse width can be arbitrarily determined.
[0037]
The subtracting unit 21 subtracts each pulse width of the print data D4-1 to D4-1 from the target modulation value TPW, and outputs the result as first to fourth subtraction values DPW-1 to DPW-4. The light quantity correction data converter 400 converts the first to fourth subtraction values DPW-1 to DPW-1 to first to fourth light quantity correction data PC-1 to PC-4 when the variation correction command BC is given.
[0038]
As described above, the pulse width correction device 11 captures the print data D4-1 to D4 output from the PWM pulse generation units 303 to 306 included in the pulse width modulation device 10, and outputs a plurality of light amount correction data (pulse width correction data). Data) PC-1 to PC-4 are obtained.
[0039]
FIG. 6 shows an example of a configuration diagram of the pixel clock selection unit 4.
[0040]
The pixel clock selection unit 4 includes four selectors 4-1 to 4-1. During normal printing, the pixel clocks PCK-1 to PCK-4 supplied from the printer I / F 12 are output as selected pixel clocks SPCK-1 to SPCK-4, respectively. . When the variation correction command BC is given, the selectors 4-1 to 4-1 select the pixel clock PCK-1 and output the selected pixel clocks SPCK-1 to SPCK-1 (= PCK-1).
[0041]
FIG. 7 shows an example of an optical system of the electrophotographic laser printer 3.
[0042]
When the LD drivers 40 to 43 shown in FIG. 2 input the print data D4-1 to D4, drive currents I1 to I4 are supplied to the LDs 44 to 47. When the LDs 44 to 47 emit light, four laser beams 501 are generated. The four laser beams 501 are incident on the rotating polygon mirror 502.
[0043]
The four laser beams 501 are focused on the surface of the photosensitive drum 503 to form beam spots, and these are deflected and scanned in the main scanning direction (the axial direction of the photosensitive drum 503) with a phase difference. Since there are four laser beams 501, four scanning lines 504 can be recorded in parallel in one scan. The photoconductor drum 503 is rotating, and the direction opposite to the rotation direction of the photoconductor drum 503 is the sub-scanning direction.
[0044]
On the photoconductor drum 503, when the respective laser beams 501 are first to fourth laser beams from the upstream in the sub-scanning direction, and their scanning positions are first to fourth laser beam scanning positions 506 to 509, Since each laser beam crosses the beam detector 505 at the head position of one scan, four beam detection signals BD are generated with a phase difference in one scan. Image data of each laser beam is generated in synchronization with each BD signal.
[0045]
Next, the operation will be described.
[0046]
First, the operation for performing normal printing will be described with reference to FIG.
[0047]
The image data D1 generated by the host computer 1 is input to the RIP developing device 9 via a network or the like. Since the image data D1 is in a page description language, the RIP developing device 9 develops the image data D1 for each page, generates a raster image which is an array of two-dimensional image data, and enables gradation expression. Is stored as the multivalued image data D2. When the multi-value image data D2 is stored in the RIP developing device 9, the printer I / F 12 transmits a print request signal PREQ to the laser printer 3. Upon receiving the print request signal PREQ, the laser printer 3 outputs a beam detection signal BD shown in FIG.
[0048]
Upon receiving the beam detection signal BD, the printer I / F 12 separates and outputs the beam detection signals BD-1 to BD-4 as shown in FIGS. 8B, 8E, 8H and 8K. The pixel clocks PCK-1 to PCK-4 shown in FIGS. 8C, 8F, 8I and 8L which are synchronized with the respective beam detection signals BD-1 to BD-4 are generated.
[0049]
FIG. 8 shows the relationship between the beam detection signals BD-1 to BD-4 of the laser printer 3, the image data D4-1 to D4 obtained from the pulse width modulator 10, and the image clocks PCK-1 to PCK-4.
[0050]
Specifically, a first pixel clock PCK-1 is generated with a time t delay from the first beam detection signal BD-1 separated from the beam detection signal BD, and the first pixel clock PCK-1 is generated in synchronization with the first pixel clock PCK-1. One image data D4-1 is generated. Similarly, the second image data D4-2 is synchronized with the second beam detection signal BD-2, and the third image data D4-3 is synchronized with the third beam detection signal BD-3. The fourth image data D4-4 is generated in synchronization with the fourth beam detection signal BD-4.
[0051]
The reason why the beam detection signals BD-1 to BD-4 and the image data D4-1 to D-4 are synchronized is that the delay time t can be ignored in practical use.
[0052]
During normal printing, the variation correction command BC of the variation correction command unit 6 is at the “0” level, and the pixel clock selection unit 4 outputs the beam detection signals BD-1 to BD-4 as selected pixel clocks SPCK-1 to SPCK-4. And outputs each of the pixel clocks PCK-1 to PCK-4 generated in synchronization with.
[0053]
The beam synchronizer 30 converts the multi-valued image data D2 output from the RIP developing device 9 into beam detection signals BD-1 to BD-4 using the respective beam detection signals BD-1 to BD-4 and the selected pixel clocks SPCK-1 to SPCK-4. Are output to the pulse width modulation device 10 as multi-valued image signals D3-1 to D4 synchronized with.
[0054]
Since the pulse width modulation device 10 corrects the pulse width variation by the pulse width correction device 11 as described later, the multi-valued image data D3-1 to D4-1 are converted into pulse width modulated print data D4-1 to D-4. Then, it is output to the laser printer 3. Since the laser printer 3 performs printing with the print data D4-1 to D4 having no pulse width variation, printing can be performed with a uniform print dot size.
[0055]
Next, the pulse width variation correction operation of the pulse width modulation device 10 will be described with reference to FIGS.
[0056]
When performing the pulse width variation correction operation, the variation correction command unit 6 sets the variation correction command BC to the “1” level. The variation correction command BC is generated by the variation correction command generator 6 when the power of the printer controller 2 is turned on or by a variation correction request command BCREQ from outside.
[0057]
When the variation correction command BC is given to the laser printer 3, the beam detection signal BD is input from the laser printer 3 to the printer I / F 12, and the pixel clocks PCK-1 to PCK-4 are generated in the same manner as in the normal printing operation described above. You.
[0058]
At the time of the pulse width variation correction, the variation correction command BC becomes “1” level, so that all of the selected pixel clocks SPCK-1 to SPCK-4 of the pixel clock selector 4 are the first pixel clock PCK-1 as shown in FIG. become.
[0059]
Further, the correction data D6 generated by the correction data generation unit 5 according to the variation correction command BC is output to the beam synchronization unit 30, and the multi-value image data D2 of the RIP developing device 9 is stopped.
[0060]
The multivalued image data D3 (correction data D6) output from the beam synchronization unit 30 is generated in synchronization with the first pixel clock PCK-1 as shown in FIG. 9B. Also, outputs D4-1 to D4 of the PWM pulse generators 303 to 306 are generated in synchronization with the first pixel clock PCK-1 as shown in FIGS.
[0061]
As described above, the outputs D4-1 to D4 of the PWM pulse generators 303 to 306 are generated in synchronization with any of the pixel clocks PCK-1 to PCK-4, so that the pulse width variation can be corrected.
[0062]
Although the print data D4 is also generated at the time of correcting the pulse width variation, the print operation is not performed because the print request signal PREQ is not input to the laser printer 3.
[0063]
The pulse widths pw1 to pw4 of the print data D4-1 to D4 shown in (c) to (f) of FIG. 9 are all different. This and the correction according to the present invention will be described with reference to FIG.
[0064]
FIG. 11 shows multi-valued image data D3 input to the PWM pulse generators 303 to 306 constituting the pulse width modulation device 10, print data D4 output from the multi-valued image data D4, and printing on recording paper by light emission of the LD light sources 44 to 47. FIG. 4 is a characteristic diagram illustrating a relationship between a dot size in the main scanning direction.
[0065]
When the number of PWM pulse generators constituting the pulse width modulation device is plural, the relationship between the multi-level image data D3 and the print data D4 is different as shown in FIG.
[0066]
For example, when the monitor image data SD1 is input as the multi-valued image data D3, the pulse width modulation values (print data) D4-1 to D4 output from the PWM pulse generation units 303 to 306 become pw1 to pw4. , The print dot size is W1 to W4.
[0067]
In the present invention, for example, the pulse width pw4 of the output D4-1 of the PWM pulse generation unit 306 is set to the target modulation value (reference pulse width) TPW, and the respective subtraction values pw4-pw1, pw4-pw2, and pw4-pw3 are set. , And generates light amount correction data PC-1 to PC-4. That is, by generating the light amount correction data PC so that each subtraction value becomes “0” (the same pulse width pw4), the print dot size can be set to W4 for any laser beam. .
[0068]
In FIG. 11, the relationship between the multi-valued image data D3 and the print data D4 is shown as being linear, but correction can be made in the same manner when the data is curved.
[0069]
Now, the operation of the above-described pulse width variation correction will be described in more detail with reference to the time chart of FIG.
[0070]
When the variation correction command BC is input, multi-valued image data D3 shown in FIG. 9B synchronized with the pixel clock SPCK-1 shown in FIG. 9A is input, and the pulse width modulation device 10 The first to fourth print data D4-1 to D4 shown in FIGS. 9C to 9F synchronized with SPCK-1 are generated.
[0071]
The target value setting unit 20 uses one of the print data (pulses) D4-1 to D4 transmitted from each of the PWM pulse generation units 303 to 306 of the pulse width modulation device 10 as a guide to know the variation of the pulse width modulation value. It is selected (set) as a (reference) target value, and is output to the subtraction unit 21 and the light quantity correction data conversion unit 400 as a target modulation value (reference pulse width modulation value) TPW.
[0072]
In FIG. 9, the print data D4-4 shown in FIG. 9 (f) having the largest pulse width among the print data D4-1 to D-4 is set as the target modulation value TPW as shown in FIG. 9 (g). The order of the pulse width to be selected as the target modulation value TPW is arbitrary.
[0073]
The subtraction unit 21 subtracts each pulse width of the first to fourth print data D4-1 to D4 from the target modulation value TPW, and subtracts the first to fourth subtractions in FIGS. 9H to 9K. Output as values DPW-1 to DPW-4.
[0074]
In this manner, the magnitude of the subtraction value, that is, the magnitude of the pulse width deviation of the pulse width of the print data D4-1 to D-4 with respect to the target modulation value TPW is converted into light quantity correction data, that is, the magnitude of the light quantity correction time. Is done.
[0075]
The operation of the PWM pulse generation unit 303 for correcting the print data D4-1 using the light amount correction data PC-1 obtained in this manner will be described with reference to the time chart of FIG.
[0076]
The reference clock SCK shown in FIG. 10G is obtained by dividing the pixel clock PCK-1 by −１. In FIG. 10, eight odd-numbered (DCK-1, DCK-3,...) Eight out of the sixteen delayed clocks DCK generated by the delayed clock generator 201 are shown in FIGS. ing.
[0077]
The delay time measuring unit 202 measures the delay time of the delay clock DCK periodically or irregularly, such as when the apparatus is started up or immediately before the image forming process, by receiving the delay time measurement command signal MES. That is, the rising edge of the reference clock 215 (time T1) is used as the sampling clock 234, and the delay clock DCK that obtains the delay time corresponding to the time t0 of one pixel is selected. In the illustrated example, the delay clock DCK-11 (t6) and the delay clock DCK-13 (t7) whose state of the delay clock changes from “1” to “0” immediately before and after the time T1 are detected. Accordingly, it is determined that the delay clock DCK-11 (t6) is a delay clock that obtains a delay time corresponding to t0, and “11” is output as the delay time measurement value 208 in decimal.
[0078]
The delay clock selection unit 203 selects a desired number falling within the time of the delay time measurement value DLT from the generated 16 delay clocks DCK. The desired number is determined according to the maximum number of gradations of the input image information or the required halftone number of the output image. In the illustrated example, the odd-numbered clocks DCK-1 to DCK-11 included within the time of the measured value DLT are odd-numbered so that the differences in the pulse widths of the generated pulses GPW are equal as shown in FIGS. Six delayed clocks SDCK are selected and output from the buffer gate.
[0079]
In addition to the method of selecting the delay clock SDCK, besides equalizing the pulse width difference, for example, the delay clock SDCK may be selected so that the pulse width ratio of the generated pulse GPW is constant.
[0080]
The pulse generation unit 204 performs a logical operation on the reference clock SCK and the six selected delay clocks SDCK, and generates six pulses GPW-1 to 6 shown in FIGS.
[0081]
The pulse selecting unit 205 receives the multi-valued (eight-stage) image data D3-1 and outputs the six generated pulses 210 and eight pulses including all white (all 0) and all black (all 1). One is selected and output as print data APW modulated in the time axis direction (pulse width modulation).
[0082]
In FIG. 10, during the period from time T0 to T1, the multi-level image data D3-1 shown in FIG. 10B is “2” (decimal number), so that the pulse selecting unit 205 shown in FIG. The generated pulse GPW-2 is output to become the print data APW shown in FIG. In the period from time T1 to time T2, the multi-level image data D3-1 shown in FIG. 10B is “5” (decimal number), so that the pulse selecting unit 205 generates the generated pulse GPW-5 shown in FIG. Is output to become the print data APW.
[0083]
The pulse width adjustment unit 420 delays the print data APW-1 shown in FIG. 10C by a time according to the light amount correction data PC-1 to generate the delayed print data DAPW of (e). The selector 495 in FIG. 4 performs this function.
[0084]
Therefore, the time differences t11 and t12 between the print data APW shown in FIG. 10C and the reference clock SCK shown in FIG. 10E correspond to the subtraction value DPW-1 shown in FIG. In comparison, as shown in FIG. 10E, the pulse width is increased by the times t11 and t12, and the print data D4-1 is generated.
[0085]
In this way, the printing is performed by the multi-beam. At the time of the variation correction, the variation of the print data (pulse width modulation value) is obtained by performing the pulse width modulation operation in synchronization with each PWM pulse generation unit, and based on the variation. To correct the pulse width. Accordingly, the emission energy of each beam contributing to the printing dots becomes the same, so that image data can be printed with high quality.
[0086]
Further, since the output pulse (print data) of one PWM pulse among the plurality of PWM pulse generators is used as the reference pulse width, the operation can be performed without providing a new device for setting the reference pulse width.
[0087]
Further, the pulse width modulation processing of a plurality of PWM pulses can be performed synchronously, that is, the processing can be restricted by simply selecting a pixel clock.
[0088]
【The invention's effect】
As described above, according to the present invention, since the pulse widths of the pulse width modulators for setting the light amounts of a plurality of laser beams are corrected to be equal, the print dot size by each laser beam can be made equal. Thus, image data can be printed with high image quality.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing one embodiment of the present invention.
FIG. 2 is a configuration diagram showing a main part of FIG. 1 in detail.
FIG. 3 is a detailed configuration diagram of a PWM pulse generator of FIG. 2;
FIG. 4 is a detailed configuration diagram of an example of a pulse width adjustment unit in FIG. 3;
FIG. 5 is a diagram illustrating an example of a configuration of a pulse width correction device illustrated in FIG. 1;
FIG. 6 is a diagram illustrating an example of a configuration of a pixel clock selection unit illustrated in FIG. 1;
FIG. 7 is a diagram illustrating an example of an optical system of the laser printer of FIG. 2;
FIG. 8 is a time chart for explaining the operation of the present invention.
FIG. 9 is a time chart for explaining the operation of the present invention.
FIG. 10 is a time chart for explaining the operation of the present invention.
FIG. 11 is a characteristic diagram of image data and print dot size for describing the present invention.
[Explanation of symbols]
2. . . 2. printer controller; . . Laser printer, 4. . . 4. Pixel clock selection unit; . . 5. a correction data generator; . . 9. Variation correction command section, . . 10. a pulse width modulator; . . Pulse width correction device, 40-43. . . Laser drive device, 44-47. . . Laser light source, 303-306. . . PWM pulse generator.

Claims (5)

A laser printer that prints image data by scanning with a plurality of laser beams each having a phase difference, and a pulse width is set according to the number of delay elements used for each of the plurality of laser beams, A pulse width modulation device that includes a plurality of pulse generation units that perform pulse width modulation of image data, and outputs a pulse obtained from these pulse generation units to the laser printer as print data; and a pulse that is output by the plurality of pulse generation units. A pulse width correction device for comparing a pulse width with a reference pulse width, and correcting a pulse width set by the delay element in the plurality of pulse generation means based on each pulse width deviation. Printer device. A pulse width is set according to the number of laser elements used and a laser printer that prints image data by scanning a photosensitive member with a plurality of laser beams each having a phase difference. A pulse width modulation device having a plurality of pulse generation means for giving the pulse width-modulated pulse to the laser printer as print data, a synchronization processing restriction means for performing the pulse width modulation processing in synchronization with the plurality of pulse generation means, A pulse width correction device that corrects a pulse width set by the delay element for each of the pulse generation units so that each of the pulse widths output by the plurality of pulse generation units during the synchronization processing matches a reference pulse width. A multi-beam printer device. A laser printer that scans the photoconductor by giving a phase difference to each of a plurality of laser beams and prints image data, and a pulse width is set according to the number of delay elements used, and pulse width modulation of the image data is performed. A pulse width modulation device having a plurality of pulse generation means for giving the generated pulse as print data to the laser printer; a synchronization processing restriction means for causing the plurality of pulse generation means to perform pulse width modulation processing in synchronization; and The pulse width of one of the pulses generated by the pulse generation means during the synchronization processing is set as a reference pulse width, and each of the pulse generation means is set such that the pulse widths of the plurality of pulse generation means coincide with the reference pulse width. A pulse width correction device for correcting a pulse width set by the delay element every time. The printer device. A laser printer that prints image data by scanning a photoconductor by giving a phase difference to each of a plurality of laser beams, and a pulse width is set according to the number of each of a plurality of delay elements used , and a pulse width of the image data A pulse width modulation device having a plurality of pulse generation means for providing modulated pulses to the laser printer as print data; a synchronization processing restriction means for causing the plurality of pulse generation means to perform pulse width modulation processing in synchronization; Correction image data generating means for providing the image data for correction to the plurality of pulse generating means during the synchronization processing of the pulse generating means, and a pulse of one of the pulses generated by the plurality of pulse generating means during the synchronization processing The width is defined as a reference pulse width, and the pulse widths of the plurality of pulse generation means are adjusted so as to match the reference pulse width. A pulse width correction device that corrects a pulse width set by the delay element for each pulse generation unit. A laser printer that has a beam detector that detects a plurality of laser beams emitted from the laser light source with a time difference, scans a photosensitive member with the plurality of laser beams and prints image data, and a plurality of laser printers connected in series A pulse width modulation device having a plurality of pulse generation means for setting a pulse width according to the number of delay elements used and providing a pulse width-modulated pulse of the image data to the laser printer as print data; and a beam of the beam detector. A printer interface unit for generating a pixel clock in synchronization with a detection signal; and selecting the pixel clock during pulse width correction and supplying the selected pixel clock to the plurality of pulse generation units, and synchronizing pulse width modulation processing with the plurality of pulse generation units. And a plurality of pulse generators output during synchronization processing. Multibeam printer apparatus characterized by comprising a pulse width correction device for correcting the pulse width in which the set by the delay element for each pulse generating means so that the pulse width is equal to the reference pulse width.

Images