JP3481421B2 - Image recording device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for recording a two-color or multicolor image by using a plurality of laser beams, and is particularly applied as an electrophotographic recording system for a copying machine, a printer, a FA, etc. The present invention relates to an image recording device.

[0002]

2. Description of the Related Art In an optical system using a plurality of laser beams, the distance from the reflection position reflected by a polycon mirror to the exposure position of a photosensitive member does not exactly match due to temperature variations such as component tolerance and assembly tolerance. , The image magnification by each laser beam will be different. Particularly, in a color printer or copying machine having two or more colors, color misregistration occurs and the image quality is deteriorated.

To solve this problem, Japanese Patent Laid-Open No. 3-25
In Japanese Patent No. 9167, the first beam system has a reference clock, image data is transferred by the output of the first clock signal generation circuit corresponding to the scanning speed, and the other beam systems use the first clock. The image data is transferred from the output of the signal generating circuit by the output of the second clock signal generating circuit corresponding to the scanning speed of another system, and the clock frequency of the second clock signal generating circuit shifts the position (image The technology disclosed is configured so that it can be set according to the (magnification).

[0004]

However, in the above prior art, the second beam system generates the clock from the output from the first clock signal generation circuit to generate the second clock signal. The circuit output is a clock corresponding to the scanning speed and is in synchronism with the scanning start position, resulting in discontinuous clock output. Therefore, when the second clock generation circuit is a closed loop such as a PLL (phase locked loop circuit), it follows the input (first clock generation circuit output), so that the output does not follow when there is no clock. Correspondence is required. Further, in the above-mentioned prior art, as an embodiment, in order to set the clock start timing of the above-mentioned second clock generation circuit as a method of synchronizing the scanning start position of the second clock generation circuit, a second PLL circuit is used. Although the horizontal synchronizing signal of the beam is directly taken in, the PLL circuit has a closed loop, which delays the response, and high-speed synchronization cannot be achieved. Further, in the above-mentioned configuration, mechanical adjustment such as inclination is required in the plurality of optical systems, and it is difficult to perform adjustment independently of mechanical magnification adjustment, and adjustment takes time. It is an object of the present invention to provide a two- or multiple-beam type image recording apparatus that can easily achieve the above-mentioned object with a simple circuit configuration.

[0005]

In order to solve the above-mentioned problems, the present invention according to claim 1 provides a plurality of laser beams modulated based on respective image signals corresponding to a plurality of scanned media . An image recording apparatus for forming an image on the medium to be scanned while scanning the plurality of medium to be scanned, comprising a plurality of laser beam generating means for generating a plurality of laser beams including a reference laser beam , the s laser beam generating means respectively, and a position detecting means for detecting the scanning start position for each one line scanning, and a plurality of clock generation means for transferring the image signal to the image modulating means
The reference laser beam clock generating means of the plurality of clock generating means includes a reference clock generator for generating a reference clock, an output of the reference clock generator and the reference laser beam position detecting means. is more configured on the reference synchronizing clock generator for generating a reference of the synchronizing clock from the output, the other clock generating means,
A variable clock generator that receives the output of the reference clock generator and generates a set clock frequency, and a synchronous clock is generated from the output of the variable clock generator and the output of the position detection means corresponding to the laser beam. It is composed of a synchronous clock generator , and a magnification adjustment mode.
Mode is selected by the laser beams.
Printing means for printing a test chart, and the test
Input method to input according to the comparison result comparing charts
Stage, and the variable clock according to the input by the input means
An image recording apparatus is proposed which has update control means for updating the set value of the generator .

[0006] In this case, as in the invention of claim 2, wherein the variable clock generator of the setting, rather good that stored at the nonvolatile memory means capable to change the setting value,
Also, the variable clock generator as claimed in claim 3, wherein, P
It is preferable to use an LL (phase locked loop). It
In addition, according to the invention of claim 4, from the input means
The number of magnification change steps is input according to the comparison result,
The update control means is adapted to
Update the setting value of the variable clock generator. For example, before
The test chart is based on the standard
Is printed according to the reference synchronization signal by the clock generation means.
The first bar printing and the other clock generating means.
With a second bar print printed in response to a sync signal
And the combination of the first bar printing and the second bar printing.
Change the above magnification so that the positional relationship with respect to the specified positional relationship
Steps are given to the update control means.

According to the first aspect of the invention, since the plurality of clock generating means for setting the respective beam frequencies are generated by the reference clock, they can be independent of each other, and the input of the clock generating means other than the reference is continuous. Since the reference clock is input, the device is simple and stable.
Further, since the present invention electrically adjusts the magnification of the optical system, the adjustment can be performed independently of other adjustments of the optical system, and the adjustment time can be shortened. According to the second aspect of the present invention, the set values of the variable clock generator are backed up and saved in the non-volatile memory means, and the set values can be changed / saved according to the device, environment and the like. According to the third aspect of the present invention, by using the PLL as the variable clock generator, a highly accurate and stable clock generator can be constructed. Claim 4
According to the described invention, the comparison result is obtained from the input means.
The number of steps to change the magnification can be entered according to
6. The set value can be arbitrarily changed by
According to the invention of the invention, the relative position of the bar printing of the test chart
Change the magnification step so that the relationship becomes a predetermined positional relationship.
Since the setting value is changed by inputting, the user can easily
The set value can be changed and saved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but merely illustrative examples. Nothing more. FIG. 1 shows an overall layout of a color printer to which the present invention is applied, and FIG. 2 shows a detailed layout of the optical system shown in FIG.

This printer is an intermediate transfer type color printer using two photosensitive drums 1 and 2, and forms a full-color image by rotating the intermediate transfer drum 3 twice. First, in the first rotation, a black image is formed on the photosensitive drum 1, and a cyan image is formed on the photosensitive drum 2. The two formed images are transferred and superposed on the intermediate transfer drum 3. Next, in the second rotation, a magenta image is formed on the photoconductor drum 1, a yellow image is formed on the photoconductor drum 2, and similarly, transfer and superposition is performed on the intermediate transfer drum 3. After superimposing the four colors in the two rotations, the recording paper fed from the paper cassette 4 or the selected paper feeders 5A and 5B to the registration roller 6 entrance end position is synchronized with the image start end of the intermediate transfer drum 3. By transferring the image to the transfer roller 7, the image is transferred and transferred, and is conveyed to the fixing roller pair 9 through the conveying system 8 to perform the image fixing. Take the configuration to end.

In FIG. 1, 11 is an intermediate drum cleaning unit, 12A and 12B are respective photosensitive drums 1,
2 is a static elimination charging cleaning unit. Also 14B,
14M, 14C and 14Y are developing units for black, magenta, cyan and yellow, respectively, and 15B and 15
M, 15C, and 15Y are black, magenta, cyan, and yellow developing cartridges, respectively.

FIG. 2 shows an optical system for exposing the two photosensitive drums 1 and 2. The optical system includes a polygon mirror 2 at a position above the center of the photoconductor drums 1 and 2 with the photoconductor drums 1 and 2 interposed therebetween.
1 is provided, and laser oscillators 22A and 22A are provided on the left and right sides of the polygon mirror on the beam incident position side, respectively.
B, collimators and incident lens groups 23A and 23B each including a cylindrical lens, and Fθ lens groups 24A and 24B on the beam emission position side of the polygon mirror and a scanning beam after passing through the lens groups to the photosensitive drums 1 and 2. Deflection mirrors 25A and 24B are provided, and a light receiving sensor (horizontal synchronization signal detection circuit) PD1, which detects a scanning start position for each line scanning, in a beam scanning area deviated from the image forming area of the scanning beam, PD2 is provided.

FIG. 3 shows a video data output circuit for outputting a corresponding video data at a predetermined frequency to the magnification adjusting circuit of the plurality of optical systems, more specifically, to the laser modulators (laser drive circuits) of the respective laser oscillators. FIG. 4 is a circuit block diagram showing an output control circuit, and FIG. 4 is an output timing diagram of the video data. In this embodiment, the circuit is configured with the photosensitive drum 1 as a reference. First, the crystal oscillator 31 is oscillated by the reference oscillator 32 as a reference clock,
Get the reference clock. This reference clock is used as it is as the video clock VCLK1 of the photosensitive drum 1, and a clock 1 synchronizing circuit 33 for synchronizing with the scanning start position detection.
Supply to. Regarding this reference clock, double clock oscillation may be performed, frequency division may be performed by 1/2, and duty may be evenly supplied.

Video clock VCLK of the photosensitive drum 2
2 is generated by the PLL synthesizer 40 and supplied to the clock 2 synchronizing circuit 34 of the photoconductor drum 2. PL
The L synthesizer 40 divides the reference clock VCLK1 from the reference oscillator 32 into 1 / M clock divider 1 /
M, a variable clock frequency divider 1 / N which is provided on the feedback side and is frequency-divided based on a set value N stored in a backup memory 46 formed of a non-volatile memory under the control of the CPU 45, and the two divided clocks. A phase comparator 41 for comparing the phase frequencies set by the frequency divider, a voltage controlled oscillator 43 for taking in the deviation of the two phases via a low-pass filter 42 and outputting VCLK2 corrected corresponding to the deviation of the phase. And the variable clock divider 1
The set value of / N is backed up and saved in the backup memory 46, and the set value can be changed / saved according to the device, environment, etc. under the control of the CPU 45.

The resolution of the video clock VCLK2 is VC
The frequency that can be set by LK1 / M is determined by the set value N of the clock frequency divider 1 / N on the feedback side. Since the resolution is almost determined by the specifications of the device, generally, the set value of the clock divider 1 / M should be a fixed value M, and the set value N of the clock divider 1 / N on the feedback side should be changed. The frequency can be changed by, and the image magnification can be finally changed. The change in magnification at this time is calculated by the following equation. K = {(VCLK1 / M) * N} / VCLK1 = N / M N = 1, 2, 3 (integer) M = const (constant)

By making the values of N and M large, it is possible to finely set the frequency, and thus the magnification can also be finely set. Now, the video clocks of the photosensitive drum 1 and the photosensitive drum 2 are clocks 1 and 2 of the respective synchronizing circuits 33 and 34.
To the synchronizing circuits 33, 3 as shown in FIG.
4, the scanning start position detector PD1 of each beam system,
Synchronized with PD2, synchronized video clock SVCLK1,
SVCLK2 and image transfer control signal VDEN
B1n and VDENB2n are buffer memories 37, 3
Output to 8. Synchronous video clock S of the photosensitive drum 1
VCLK1 and image transfer control VDENB1n are
It becomes effective with a delay of td1 from the scanning start position PD1, and the synchronous video clock SVCLK2 of the photosensitive drum 2
The image transfer control SVDENB2n becomes valid after a delay of td2 from the scanning start position PD2. Image data read from the image memories 35 and 36 are serially transferred according to the synchronous video clock after each signal becomes valid, and the video signals VDO1 and VDO2 are sent to the laser modulators (laser drive circuits) 28A and 28B. Thus, modulated lasers corresponding to the video signals VDO1 and VDO2 are generated, and beam output from the laser oscillators 22A and 22B to form the latent image shown in FIGS. 1 and 2 on the corresponding photoconductor drums 1 and 2.

FIG. 5 is a flow chart for adjusting the magnification of the optical system, and FIGS. 6 and 7 show the states before and after the adjustment of the optical system magnification test chart. In FIG. 5A, first, when the power of the device is turned on, initialization is performed (S
1), the set value N is loaded from the backup memory 46 and the variable clock frequency divider 1 / of the PLL synthesizer 40 is loaded.
The set value N of N is set (S2), and after that, the process proceeds to the main processing routine (S3), where printing such as full-color printing can be performed. When the color shift due to the magnification becomes noticeable in full-color printing or the like, the user selects the magnification adjustment mode from the front panel as shown in FIG.

When the magnification adjustment mode shown in FIG. 5 (C) is selected, the magnification adjustment mode routine is activated, and it is first confirmed whether or not the test chart is printed. (S6) When the print of the test chart is selected, the test charts of FIGS. 6 and 7 are printed. In the left printing results in this test chart, the vertical bar (first bar printing) of drum1 but must be located in the center of the vertical bar block of Drum2 (second bar printing), small magnification 6 And is off the center. In this case, it is necessary to adjust the magnification (S7), and the number of magnification changing steps is input from the front panel so that the magnification is the same. (S8) This magnification changing step is the resolution 1 / of the PLL synthesizer.
The step resolution is determined by M. When the magnification change step number is input, the N value of the PLL synthesizer is rewritten, and then the value of the backup data is also updated. (S9) After the change process is completed, the test chart is printed again to check whether the magnifications are the same with the test chart shown in FIG. If the change result can be predicted in advance, it is not always necessary to print the test chart after the magnification change processing, and the magnification adjustment mode may be ended.

[0018]

As described above, according to the present invention, since the plurality of clock generation means generate from the reference clock,
The clock generating means other than the reference can be independent of each other, and a continuous reference clock is input to the input of the clock generating means. Therefore, the device is simple and stable. Also, the set values of the variable clock generator are backed up and saved, and the set values can be changed / saved according to the equipment, environment, etc. Furthermore, the set value of the variable clock generator can be changed and saved by the user by changing the set value according to the printout (test chart).
I can. Furthermore, as a variable clock generator, PL
By using L, a highly accurate and stable clock generator can be constructed. Further, since the present invention electrically adjusts the magnification of the optical system, the adjustment can be performed independently of other adjustments of the optical system, and the adjustment time can be shortened.

[Brief description of drawings]

FIG. 1 is an overall layout diagram of a color printer to which the present invention is applied.

FIG. 2 is a detailed layout diagram of the optical system of FIG.

FIG. 3 is a video data output control for outputting corresponding video data at a predetermined frequency to a magnification adjusting circuit of a plurality of optical systems shown in FIG. 2, more specifically to a laser modulator (laser driving circuit) of each laser oscillator. It is a circuit block diagram which shows a circuit.

FIG. 4 is an output timing chart of the video data.

FIG. 5 is a flowchart of magnification adjustment of the optical system.

FIG. 6 is a diagram showing a state before adjustment of an optical system magnification test chart.

FIG. 7 is a diagram showing a state after adjustment of an optical system magnification test chart.

[Explanation of symbols]

1, 2 photoconductor drum 3 Intermediate transfer drum 14B, 14M, 14C, 14Y each color development unit 21 polygon mirror 22A, 22B Laser oscillator PD1, PD Horizontal sync signal detection circuit 31 crystal unit 32 Reference oscillator 33 clock 1 synchronization circuit 40 PLL synthesizer 34 Clock 2 synchronization circuit 32 Reference oscillator 1 / M clock divider 46 backup memory 1 / N variable clock divider 41 Phase comparator 42 low pass filter 43 Voltage controlled oscillator

Claims (5)

(57) [Claims] 1. A forming an image on the medium to be scanned while scanning the plurality of the medium to be scanned by a plurality of laser beams modulated based on the corresponding respective image signals to a plurality of medium to be scanned The image recording apparatus has a plurality of laser beam generating means for generating a plurality of laser beams including a reference laser beam, and each of the laser beam generating means detects a scanning start position for each line scanning. Means and a plurality of clock generating means for transferring the image signal to the image modulating means
A reference laser beam clock generation means of the plurality of clock generation means, a reference clock generator for generating a reference clock, an output of the reference clock generator, and the reference laser beam position detection means. Reference Synchronous Clock Generator that Generates Reference Synchronous Clock from Output
It is more configured bets, the other clock generating means, a variable clock generator for generating an input to set the clock frequency output of the reference clock generator, corresponding to the laser beam and the output of the variable clock generator composed of a synchronous clock generator for the output of the said position sensing means generating a synchronous clock
It is further, when the magnification adjustment mode is selected, the plurality of
Printing to print a test chart with a laser beam
According to the comparison result comparing the means and the test chart
The input means for performing the input and the input by the input means.
Control for updating the set value of the variable clock generator
An image recording apparatus comprising means. 2. The image recording apparatus according to claim 1, wherein the set value of the variable clock generator is stored in a non-volatile memory means capable of changing the set value. 3. The variable clock generator comprises a PLL (phase
Locked loop) image recording apparatus according to claim 1 or 2, wherein the configured using. 4. According to the comparison result from the input means
The number of magnification change steps is input, and the update control means
The variable clock generator according to the number of steps for changing the magnification
The set value of is updated.
1. The image recording device according to 1. 5. The test chart is a reference chart.
The synchronization signal of the reference by the ZarBeam clock generation means.
The first bar printed according to the number and the other
The second bar printed in response to the synchronization signal generated by the clock generation means.
Printing, the first bar printing and the second bar printing
Before the relative positional relationship with the printing becomes the predetermined positional relationship
A step of changing the magnification is given to the update control means.
The image recording apparatus according to claim 5, wherein