JPH05330128A - Apparatus for measuring beam interval, displaying beam output distribution and adjusting beam material - Google Patents

Abstract

PURPOSE:To simply measure a beam interval in an image forming apparatus forming an image using multibeam. CONSTITUTION:Two laser beams are emitted from a laser device 31 and altered by a polygonal mirror 34 to scan the high speed optical sensor 43 and unidimensional image sensor 44 of a beam interval measuring device through an ftheta lens 35. The data of the unidimensional image sensor 44 is read in specified timing after the laser beam is detected by the high speed optical sensor 43 and the interval between two laser beams is calculated. Since the unidimensional image sensor 44 is obliquely arranged, beam interval is easily measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam interval measuring device used in an image forming apparatus such as a laser printer or an electrophotographic copying machine which forms an image by simultaneously using a plurality of light beams such as a laser beam, and The present invention relates to a beam output distribution display device for displaying what kind of beam intensity distribution can be obtained at each beam interval, and a beam interval adjustment device capable of optimally adjusting the beam interval.

[0002]

2. Description of the Related Art Many image forming apparatuses such as laser printers and electrophotographic copying machines are adapted to form an electrostatic latent image on a photosensitive member and develop the electrostatic latent image with toner to record the image. .. In such an apparatus, it is usual to form one type of image using one laser beam, but it has also been proposed to form an image more quickly using a plurality of laser beams.

For example, in Japanese Examined Patent Publication No. 64-10805, a plurality of light source units arranged in an array are used to generate a plurality of beams such as laser beams (hereinafter simply referred to as multi-beams). Then, these multi-beams are converged by a collimating optical system so as to be spatially concentrated as much as possible, and the plurality of obtained light beams are simultaneously deflected by a deflector to scan the photosensitive drum.

Further, in Japanese Patent Publication No. 1-45065,
A plurality of light source parts are used, and a plurality of beam spots by these light source parts scan the scanning lines on the photosensitive drum, which are separated from each other by a predetermined distance.

As described in the above-mentioned publications, a plurality of beams are scanned in parallel at a certain interval in the sub-scanning direction in order to form an electrostatic latent image on a recording member such as a photosensitive drum at a high speed. The technology to do so is drawing attention.

FIG. 13 is a diagram for explaining the state of such multi-beam scanning. Scanning lines L ₁ , L ₂ , L ₃ , on the photoconductor on which the light beam is scanned,
It is assumed that the intervals of ... Are d, and two light beams are scanned at a beam interval D of three lines. First, in the first scan, the scan lines L ₁ and L ₄ are simultaneously scanned. The two black circles P ₁₁ and P ₁₂ shown in the figure represent the print dots created at some timing of the first time. In the second scan, the scan lines L ₃ and L ₆ are simultaneously scanned. The two black circles P ₂₁ and P ₂₂ shown in the figure are these 2
It represents a print dot created at a certain timing of the second time. In the third scan, the scan lines L ₅ and L ₈ are simultaneously scanned. The two black circles P ₃₁ and P ₃₂ shown in the figure represent the print dots created at a certain timing of the third time. In the same manner, interlace scanning of two beams and three lines is performed.

By the way, the amount of light received by a predetermined unit area of the photoconductor is the total integrated quantity of the light beam when the light beam passes through the unit area, which is a value obtained by integrating the beam intensity distribution with time. Become. Now, consider the three print dots P ₁₂ , P ₂₁ , and P ₃₁ surrounded by dotted lines in FIG. 13 as the unit area 11. These are areas formed by scanning three lines.

FIG. 14 shows an ideal light amount distribution in this unit area in the sub-scanning direction. If the intervals between the print dots P ₁₂ , P ₂₁ and P ₃₁ are set accurately as shown in this figure, these intensity distribution curves 12 ₁ and 12
_The combined intensity distribution curve 13 of ₂ and 12 ₃ has a substantially uniform intensity level.

FIG. 15 and FIG. 16 show the case where the beam intervals are different and unevenness occurs in the intervals of the respective print dots. In FIG. 15, since the two intensity distribution curves 12 ₂ and 12 ₃ are close to each other, the synthetic intensity distribution curve 14 shows a peak in the portion between them. Also,
Since the two intensity distribution curves 12 ₁ and 12 ₂ are separated from each other, the intensity distribution shows a bottom in the area between them.
In the case of FIG. 16 as well, the intensity distribution curve 15
Shows a distribution almost opposite to the distribution shown in FIG.

[0010]

FIG. 15 and FIG. 1
As shown in FIG. 6, when the beam distance D deviates from the ideal value, unevenness occurs in the light amount distribution in the sub-scanning direction. Such unevenness of the light amount distribution greatly affects the quality of an image created by a printer or the like. Therefore, some proposals have been made to measure the beam spacing of multi-beams.

FIG. 17 is for explaining the proposal using the position sensor. The position sensor 21 is
It is a sensor for detecting the position between AB when the light beam 22 is incident between the point A at one end and the point B at the other end.

On the other hand, FIG. 18 is for explaining the proposal for measuring the distance between the light beams by using the image sensor. By arranging the one-dimensional image sensor 23 perpendicularly to each light beam and detecting the light receiving pixels irradiated with light, the beam interval is obtained.

[0013]

In the first proposal of these, the position sensor 21 is used. Therefore, when one thin light beam hits it, its position can be detected, but when two light beams are simultaneously incident, there is a problem that their positions cannot be individually detected. That is, with this method, it was impossible to simultaneously measure the intervals of the light beams. Further, even if the light beams 22 are individually incident, they have the thickness required as a print dot, so that there is a problem that the position cannot be accurately specified.

Next, according to the second proposal, which light-receiving pixel of the one-dimensional image sensor 23 has detected which light beam has been detected.
It is possible to detect 4 and 25 in parallel. However, the minimum distance between the light receiving pixels of the one-dimensional image sensor 23 is about 7 μm in the current technology. Therefore, one light beam 24 (or 25) is detected by two or more light receiving pixels at the same time, and there is a problem that the beam interval cannot be measured with sufficient accuracy.

Due to these problems, the conventional image forming apparatus cannot mechanize the adjustment of the intervals of the light beams, and the adjustment is performed manually by relying on the experience of a skilled person. .. Therefore, it takes a long time for adjustment work,
Further, there is a problem that the adjustment result varies depending on the device.

Therefore, an object of the present invention is to provide a beam interval measuring device capable of easily measuring the interval between these beams in an image forming apparatus for forming an image using multiple beams.

Another object of the present invention is to measure only two light beams when performing interlaced scanning with the two light beams, estimate the actual beam output distribution, and display the degree of unevenness. It is to provide a beam output distribution display device capable of performing the above.

Still another object of the present invention is to measure only these two light beams when performing interlaced scanning with the two light beams and adjust the beam interval so that the overall output distribution becomes flat. It is an object of the present invention to provide a beam interval adjusting device that can be used.

[0019]

According to a first aspect of the present invention, there is provided an optical sensor for detecting at least one of a plurality of light beams which are simultaneously scanned in a predetermined scanning direction with a certain interval, and a plurality of light receiving pixels. Are arranged in a row at a predetermined angle which is not parallel or perpendicular to the scanning direction, and a one-dimensional image sensor for detecting the plurality of light beams, and a predetermined one after the light sensor detects the light beams A reading means for reading the output of the one-dimensional image sensor after the passage of time, and a distance measuring means for calculating the distance between the light beams by obtaining the distance between the light receiving pixels where the beam is detected from the output read by the reading means. And the beam spacing measuring device.

That is, according to the first aspect of the present invention, the one-dimensional image sensor is tilted with respect to the scanning direction of the light beam, and thereby the detected distance of the light beam is substantially increased to measure the light beam distance. make it easier.

According to a second aspect of the present invention, an optical sensor for detecting at least one of two light beams simultaneously scanned in a predetermined scanning direction with a certain interval, and a plurality of light receiving pixels are arranged in a predetermined positional relationship. A one-dimensional or two-dimensional image sensor that is arranged to detect these two light beams, a reading unit that reads out the output of the image sensor after a lapse of a predetermined time after the light sensor detects the light beams, and a reading unit. First output distribution calculating means for calculating an output distribution in the direction orthogonal to the scanning direction based on the output read by the means, and additionally scanning between these two light beams when forming an image. And a light beam interpolating means for interpolating the output distribution of the light beam by shifting an ideal interval of the scanning line when the light beam is present.
Second output distribution calculation for estimating the output distribution on the light beam scanning surface during image formation by adding the output distribution of the light beam interpolated by the light beam interpolating means to the output distribution calculated by the first output distribution calculating means The beam output distribution display device is provided with a means and an output distribution display means for displaying the degree of unevenness of the distribution due to the output distribution calculated by the second output distribution calculation means.

That is, according to the second aspect of the present invention, in an image forming apparatus for scanning multi-beams by interlaced scanning, a virtual output distribution by another scanning is added to the output distribution of the light beam detected on the image sensor. The output distribution on the surface to be actually scanned is hypothesized, and based on this, how flat the distribution is is displayed.

According to a third aspect of the present invention, an optical sensor that detects at least one of two light beams that are simultaneously scanned in a predetermined scanning direction with a certain interval, and a plurality of light receiving pixels are arranged in a predetermined positional relationship. A one-dimensional or two-dimensional image sensor that is arranged to detect these two light beams, a reading unit that reads out the output of the image sensor after a lapse of a predetermined time after the light sensor detects the light beams, and a reading unit. First output distribution calculating means for calculating an output distribution in the direction orthogonal to the scanning direction based on the output read by the means, and additionally scanning between these two light beams when forming an image. And a light beam interpolating means for interpolating the output distribution of the light beam by shifting an ideal interval of the scanning line when the light beam is present.
Second output distribution calculation for estimating the output distribution on the light beam scanning surface during image formation by adding the output distribution of the light beam interpolated by the light beam interpolating means to the output distribution calculated by the first output distribution calculating means The beam spacing adjusting device is provided with a means and a beam spacing adjusting means for adjusting the spacing between the two light beams so that the output distribution calculated by the second output distribution calculating means becomes the most flat.

That is, according to the third aspect of the invention, in an image forming apparatus for scanning multi-beams by interlaced scanning, a virtual output distribution by another scanning is added to the output distribution of the light beam detected on the image sensor. The beam interval is set to an optimum value by imagining the output distribution on the surface to be actually scanned and adjusting the interval between the two light beams so that the distribution becomes the most flat based on this.

[0025]

EXAMPLES The present invention will be described in detail below with reference to examples.

First embodiment

FIG. 1 shows a main part of an image forming apparatus using a beam interval measuring apparatus according to the first embodiment of the present invention. The image forming apparatus used in this embodiment includes a laser device 31 that outputs two laser beams at a predetermined interval in the sub-scanning direction. These two laser beams output from the laser device 31 are incident on a collimator lens 32 to be a parallel light beam, and after passing through an optical lens 33 for appropriately adjusting the beam interval, a polygon mirror 34 is provided.
Is incident on. The polygon mirror 34 is rotating at a constant speed and repeatedly deflects the two incident laser beams. After passing through the fθ lens 35, these laser beams are focused on the scanning surface (bus line) of the photosensitive drum (not shown) and scanned in the main scanning direction. As a result, the two bundles of rays that are spaced apart from each other virtually form the scanning lines 36 ₁ and 36 ₂ on the photosensitive drum.

The fixed plate 41, which constitutes a part of the beam interval measuring device, is provided with the scanning line 3 when measuring the beam interval.
It is arranged at a predetermined position parallel to 6 ₁ and 36 ₂ . A movable stage 42 is slidably arranged on the fixed plate 41. A high-speed optical sensor 43 is arranged on the left side and a one-dimensional image sensor 44 is arranged on the right side of the moving stage 42 at positions where the scanning lines 36 ₁ and 36 ₂ pass. The moving stage 42 can move on the fixed plate 41 in order to measure the beam interval at an arbitrary scanning position. The one-dimensional image sensor 44 is disposed so as to be inclined with respect to the _two scanning lines 36 ₁ and 36 ₂ by a predetermined angle, and detects the light beam at a predetermined timing after the high-speed optical sensor 43 detects the light beam. Is read.

2 and 3 show the principle of detecting the beam interval by the one-dimensional image sensor. Of these, FIG. 2 shows a case where the one-dimensional image sensor 44 is arranged vertically to the _two scanning lines 36 ₁ and 36 ₂ . With such a vertical arrangement, the light beams 46 ₁ , 4
Receiving pixel 47 ₁ for detecting a 6 _2, 47 ₂ of the interval,
It is equal to the distance D between the light beams 46 ₁ and 46 ₂ .

FIG. 3 shows the arrangement of the one-dimensional image sensor in this embodiment. The one-dimensional image sensor 44 is inclined by an angle θ (0 <θ <90 degrees) with respect to the _two scanning lines 36 ₁ and 36 ₂ . In this case, the distance D ′ between the light receiving pixels 47 ₁ and 47 ₂ for detecting the light beams 46 ₁ and 46 ₂ is equal to the light beams 46 ₁ and 4 2.
6 ₂ distance D and the following (1) becomes a relationship shown by the formula.

[0031]

[Equation 1]

That is, as the angle θ approaches 0 degree, the distance D'has a value obtained by enlarging the distance D, so that the measurement by the one-dimensional image sensor 44 is performed more accurately.

FIG. 4 shows the structure of the data acquisition circuit of the beam interval measuring apparatus of this embodiment.
The reference clock generating circuit 51 of this device is a reference clock 5
2 is generated and is supplied to the CCD driver 53. When the CCD driver 53 is supplied with the light beam detection signal 54 from the high-speed optical sensor 43, the CCD driver clock 55 is supplied to the one-dimensional image sensor 44 by a time corresponding to one scanning line at a predetermined timing slightly after this. To supply.
At this point in time, the one-dimensional image sensor 44 is irradiated with the light beams 46 ₁ and 46 _{2 at the two positions} thereof, and charges are accumulated in the light receiving pixels 47 ₁ and 47 ₂ (see FIG. 3) corresponding to them. There is. Therefore, the one-dimensional image sensor 44
When the CCD drive clock 55 is supplied to, the image data 57 for one line is supplied to the black level correction circuit 58.

Clamp circuit 59 of black level correction circuit 58
A clamp control signal 61 is supplied from the CCD driver 53 to the input, and the noise component is removed by cutting the DC component of the input image data 57 for one line. In this way, the black level corrected image data 6
2 is input to the sample hold circuit (S / H) 63. The sample and hold circuit 63 is the timing circuit 6
The image data 62 is fetched in synchronism with the timing signal 65 supplied from the No. 4 and held until the next fetch timing, and the result is supplied to the analog-digital converter circuit (A / D) 66. There is. CC
The timing circuit 64, which receives the clock signal 67 from the D driver 53 and creates various timings, also supplies the timing signal 68 to the analog-digital converter circuit 66 to set the timing of A / D conversion. It has become.

Analog-to-digital converter circuit 6
A / D conversion result 69 for each light receiving pixel output from 6
Is a timing signal 71 supplied by the timing circuit 64.
Thus, the address is sequentially incremented and written in the working memory 72. As a result, when the writing of one line is completed, the signal level of each light receiving pixel of the one-dimensional image sensor 44 is written in the working memory 72 as a digital value.

FIG. 5 shows an outline of the overall circuit configuration of the beam interval measuring apparatus. The beam interval measuring device has a CPU (central processing unit) 81 which is the center of control. The CPU 81 is connected to various circuit components via a bus 82 such as a data bus. ROM83 of these
Is a read-only memory that stores a program for controlling each part of the beam interval adjusting apparatus.
As described above, the work memory 72 stores the data of each light receiving pixel for one line, and also temporarily stores the data necessary for performing various controls. The input circuit 84 is a circuit for inputting operation data of the keyboard 85. The display drive circuit 86 is a circuit for displaying a measurement result or the like on the liquid crystal display 87.

The contents of the measuring operation of this beam interval measuring apparatus will be described with reference to FIG. The CPU 81 (FIG. 5) first sets the count value n to “1” and, at the same time, the working memory 72.
The contents of the predetermined addresses A and B are cleared (step S101). Then, the value (here, "0") stored in the address B of the working memory 72 is moved to the address A (step S102), and the address n of the working memory 72 (here, the data about the first light receiving pixel is stored). The data of the designated "1" address is read (step S103). Then, the read value is written in the address B (step S
104). After that, the data at the address A is compared with the size at the address B (step S105). Here, the read result of the one-dimensional image sensor 44 is stored only in the address B, but since the initialized data “0” is written in the address A, the data in the address B is more than the data in the address A. Is larger or both are equal (Y).
Therefore, in this case, the count value n is incremented by "1" (step S106), and the step S1 is performed again.
Return work to 02.

In this way, the data of the next second light receiving pixel is read out (step S10).
3) The sizes of the first and second data are compared (step S105). When the magnitude relations between the light receiving pixels are successively compared in this manner, the light receiving pixel 47 ₁ shown in FIG. 3 is detected _first (step S).
105; N). That is, the light receiving values of the respective light receiving pixels are compared, and the data of the address A becomes larger than the data of the address B in the next comparison work after detecting the peak.

At this time, the CPU 81 stores the number a of the light receiving pixel in a predetermined address of the working memory 72 (step S107). Then, the count value n is further incremented by "1" (step S108), the value stored in the address B of the work memory 72 is moved to the address A (step S109), and the data of the address n of the work memory 72 is transferred. Is read (step S110). Then, the read value is written in the address B (step S111).
After this, the data at the address A is compared with that at the address B in the same manner as before (step S112). Then, while the data at the address B is larger than the data at the address A or when both are equal (Y), the process returns to step S108 and the same operation is repeated.

On the other hand, if the data at the address A becomes larger than the data at the address B (step S112;
N), the CPU 81 stores the number "b" of the light receiving pixel in a predetermined address of the work memory 72 (step S11).
3). Thus, the numbers of the light receiving pixels corresponding to the irradiation peaks of the light beams 46 ₁ and 46 ₂ in the one-dimensional image sensor 44 are obtained. Therefore, the beam interval D is obtained by multiplying the difference between these numbers by a predetermined constant C. Here, the constant C is a value that is determined by the inclination angle of the one-dimensional image sensor 44 with the spacing between the light receiving pixels. The CPU 81 uses the working memory 72 to perform this calculation, and displays the result on the liquid crystal display 87 in units of μm, for example.

Second embodiment

In the first embodiment, the beam distance measuring device for measuring the beam distance has been described. In the second embodiment, however, a beam distance adjusting device for adjusting the beam distance will be described. It should be noted that FIGS. 1, 3, 4, and 5 are used in the same manner in the second embodiment.

Now, also in the second embodiment, FIG. 1 and FIG.
Two light beams 46 ₁ and 46 ₂ using the device shown in FIG.
(FIG. 3) is scanned on the one-dimensional image sensor 44, and the result is stored in the working memory 72. And after this,
As if the photosensitive drum moves, two scanning lines 36
An imaginary state in which two sets of ₁ and 36 ₂ are further formed is created by signal processing. From this signal processing result, FIG.
The composite intensity distribution as described above is obtained, and the beam interval is adjusted so that it exhibits the flattest characteristic.

7 to 9 are for explaining such signal processing. First, the waveform shown in FIG.
The intensity distribution in the sub-scanning direction is obtained by the CPU 81 in which the disturbance light is canceled, the intensity distribution is normalized, and the inclination of the one-dimensional image sensor 44 is corrected based on the data stored in the work memory 72 shown in FIG. .. Light beam 46 ₁ ,
Intensity distribution curves 91 ₁ and 91 ₂ corresponding to 46 ₂ respectively.
The respective peaks of are spaced by X pixels. Now, it is assumed that the ideal interval between the scanning lines is d ₀ . In this case, the intensity distribution curves 91 ₁ , 91 ₂ shown in FIG.
By shifting 2 d ₀ by 2, the next scanning state on the photosensitive surface in a state where the photosensitive drum is rotated can be virtualized.

FIG. 8 shows a virtual state of the intensity distribution on the photosensitive drum. First intensity distribution curve 91 ₁
Is shifted in the sub-scanning direction by a distance 2d ₀ , and the next scanning state is assumed as an intensity distribution curve 91 ₁ ′. The second intensity distribution curve 91 ₂ is displaced by a distance 2d _{0 in the} direction opposite to the sub-scanning direction, and the previous scanning state is assumed as an intensity distribution curve 91 ₂ ′. Here, a composite waveform of the three intensity distribution curves 91 ₁ , 91 ₂ ′, 91 ₁ ′ is obtained.

FIG. 9 shows the composite output distribution thus obtained. In this example, the intensity distribution curves 91 ₂ ′ and 9 ₂ ′ and 9
The interval of 1 ₁ ′ is narrow, and the maximum value I _max of the output distribution exists between them, and the intensity distribution curves 91 ₁ and 9
There is a minimum value I _min of the output distribution between 1 ₂ ′.
When the degree of non-flatness in the combined output distribution 93 is represented by R, this can be represented by the following equation (2).

[0047]

[Equation 2]

The degree R becomes smaller as the beam spacing approaches the ideal value. Therefore, if this is displayed on the liquid crystal display 87 (FIG. 5), it is possible for the operator to recognize how much the beam interval is misaligned.

FIG. 10 shows a work flow for displaying such a degree of unevenness of the beam output distribution. First, the CPU 81 reads out the data stored in the working memory 72 in the previous embodiment (step S20).
1). Then, the first intensity distribution curve E (91 ₁ ) and the second intensity distribution curve E (91 ₁ )
Intensity distribution curve F (91 ₂ ) (step S
202). Then, the first intensity distribution curve E is shifted by the distance 2d ₀ in the sub-scanning direction as described with reference to FIG. 8 (step S203), and this is stored in the working memory 72 as the intensity distribution curve e (step S204). .. Further, the second intensity distribution curve F is shifted by a distance -2d _{0 in the} sub-scanning direction (step S205) and stored as the intensity distribution curve f in the working memory 72 (step S206).

Next, the CPU 81 adds the intensities of the three intensity distribution curves E, e, f to obtain a combined output distribution as shown in FIG. 9 (step S207). Then, from this result, the maximum value I _max and the minimum value I _min of the output distribution are sequentially obtained (steps S208 and S209). Next, the degree R where the output distribution is not flat is calculated (step S210),
This is displayed on the liquid crystal display 87 (step S211).

Modification

FIG. 11 shows a beam interval adjusting device capable of automatically adjusting the beam interval to an optimum value as a modification of the second embodiment described above. In this modification, a motor control circuit 95 is connected to the bus 82. The motor control circuit 95 moves the optical lens 33 shown in FIG. 1 by a predetermined amount, calculates the degree R each time, and fixes the optical lens 33 at a position where this is minimized. The optical lens 33 is an afocal optical system, and when the optical lens 33 is moved, only the angular magnification of the optical system changes and the beam interval is expanded or contracted. As a result, the optimum beam interval is automatically adjusted. Will be set automatically.

FIG. 12 shows an example in which a two-dimensional light receiving element is used as another modification. Even if the two-dimensional image sensor 101 is used instead of the one-dimensional image sensor as described in the embodiment, a plurality of measured beams 1
It is possible to measure the interval between 02 and 103. Based on this, the signal processing device 104 performs signal processing in the sub-scanning direction and the like, and the beam interval calculation circuit 105 calculates the beam interval by the method described above. In this modified example, by using the two-dimensional image sensor 101, it is possible to measure the distance and profile between the stationary light beams.

[0054]

As described above, according to the first aspect of the invention, the one-dimensional image sensor is arranged so as to be positively inclined with respect to the scanning direction of the light beams, and the distance between these light beams is measured. Even if the one-dimensional image sensor in which the pixel intervals are not relatively close to each other is used, there is an effect that the interval adjustment of the plurality of light beams can be performed with high accuracy.

According to the second aspect of the invention, it is possible to obtain the comprehensive output distribution characteristic of the light beam by the interlaced scanning without moving the surface of the photoconductor.
Therefore, there is an effect that the unevenness of the output distribution can be accurately calculated and displayed by excluding the variation of the measurement result due to the unevenness of the moving speed of the photoconductor in the sub-scanning direction. Further, according to the present invention, the powers of the two light beams can be similarly adjusted.

Further, according to the third aspect of the invention, the beam interval can be set to an optimum value by making the total output distribution characteristic of the light beam by the interlaced scanning the flattest. The automation can facilitate the adjustment especially at the site where the image forming apparatus is installed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of an image forming apparatus using a beam interval measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a principle of detecting a beam interval by a one-dimensional image sensor arranged so as to be orthogonal to a scanning line.

FIG. 3 is an explanatory diagram showing a principle of detecting a beam interval by a one-dimensional image sensor arranged to be inclined with respect to a scanning line.

FIG. 4 is a block diagram showing a configuration of a portion of a data fetch circuit in the first embodiment.

FIG. 5 is a block diagram showing an outline of an overall circuit configuration of the beam interval measuring apparatus in the first embodiment.

FIG. 6 is a flowchart showing a measuring operation of the beam interval measuring apparatus in the first embodiment.

7 is a characteristic diagram showing the intensity distribution in the sub-scanning direction in which the data stored in the working memory shown in FIG. 4 in the second embodiment is corrected.

FIG. 8 is an explanatory diagram showing a virtual state of intensity distribution on a photosensitive drum in the second embodiment.

FIG. 9 is an explanatory diagram showing a composite output distribution obtained in the second embodiment.

FIG. 10 is a flowchart showing a work flow for displaying the degree of unevenness of beam output distribution in the second embodiment.

FIG. 11 is a block diagram showing a main part of a circuit configuration of a beam interval adjusting device capable of automatically adjusting a beam interval to an optimum value in a modification of the second embodiment.

FIG. 12 is a schematic configuration diagram showing a main part of an apparatus using a two-dimensional light receiving element as a modified example of the invention.

FIG. 13 is an explanatory diagram showing a state of multi-beam scanning by interlaced scanning.

FIG. 14 is a characteristic diagram showing an ideal light amount distribution in a unit area in the sub-scanning direction.

FIG. 15 is a characteristic diagram showing an example in which unevenness occurs in the intervals of print dots due to different beam intervals.

FIG. 16 is a characteristic diagram showing another example in which unevenness occurs in the intervals of print dots due to different beam intervals.

FIG. 17 is an explanatory diagram showing a method of measuring the position of a light beam using a position sensor.

FIG. 18 is an explanatory diagram showing a method of measuring the distance between two light beams using a one-dimensional image sensor.

[Explanation of symbols]

31 ... Laser device, 33 ... Optical lens, 34 ... Polygon mirror, 35 ... f.theta. Lens, 36 ... Scan line, 41 ...
Fixed plate, 42 ... Moving stage, 43 ... High-speed optical sensor, 4
4 ... One-dimensional image sensor, 46 ... Light beam, 47 ... Light receiving pixel, 72 ... Working memory, 81 ... CPU, 83
... ROM, 87 ... Liquid crystal display, 96 ... Lens moving motor, 101 ... Two-dimensional image sensor, 104 ... Signal processing device, 105 ... Beam interval calculation circuit

Claims (3)

[Claims] 1. An optical sensor that detects at least one of a plurality of light beams that are simultaneously scanned in a predetermined scanning direction with a certain interval, and a plurality of light receiving pixels are parallel or perpendicular to the scanning direction. A one-dimensional image sensor which is arranged in a line at a predetermined angle that does not cause the light beams to detect a plurality of light beams, and the output of the one-dimensional image sensor is read out after a predetermined time has elapsed since the light sensor detected the light beams. Beam interval measurement, comprising: read-out means; and interval measuring means for calculating an interval between light beams by obtaining an interval between light-receiving pixels in which a beam is detected from an output read out by the read-out means. apparatus. 2. An optical sensor for detecting at least one of two light beams simultaneously scanned in a predetermined scanning direction with a certain interval, and a plurality of light receiving pixels are arranged in a predetermined positional relationship, and these two light beams are arranged. An image sensor that detects a light beam, a reading unit that reads out an output of the image sensor after a predetermined time has elapsed after the light sensor detects the light beam, and a reading unit that is based on the output read by the reading unit. A first output distribution calculating means for calculating an output distribution in a direction orthogonal to the scanning direction; and when a light beam to be additionally scanned is present between these two light beams when forming an image, A light beam interpolating means for interpolating the output distribution of the light beam at an ideal interval, and an optical beam interpolating means for calculating the output distribution calculated by the first output distribution calculating means. Second output distribution calculating means for adding the output distribution of the light beam interpolated by the optical interpolation means to estimate the output distribution on the light beam scanning plane at the time of image formation; and the second output distribution calculating means for calculating. A beam output distribution display device, comprising: an output distribution display means for displaying the degree of unevenness of the distribution due to the output distribution. 3. An optical sensor for detecting at least one of two light beams simultaneously scanned in a predetermined scanning direction with a certain interval, and a plurality of light receiving pixels are arranged in a predetermined positional relationship, and these two are arranged. An image sensor that detects a light beam, a reading unit that reads out an output of the image sensor after a predetermined time has elapsed after the light sensor detects the light beam, and a reading unit that is based on the output read by the reading unit. A first output distribution calculating means for calculating an output distribution in a direction orthogonal to the scanning direction; and when a light beam to be additionally scanned is present between these two light beams when forming an image, A light beam interpolating means for interpolating the output distribution of the light beam at an ideal interval, and an optical beam interpolating means for calculating the output distribution calculated by the first output distribution calculating means. Second output distribution calculating means for adding the output distribution of the light beam interpolated by the optical interpolation means to estimate the output distribution on the light beam scanning plane at the time of image formation; and the second output distribution calculating means for calculating. A beam interval adjusting device, comprising: a beam interval adjusting means for adjusting an interval between the two light beams so that an output distribution becomes the flattest.