JP2003042897A - Scan beam measuring apparatus and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct a scan beam measurement in working conditions nearer to an actual apparatus, with considering the beam intensity distributions overlapped on adjacent dots in the horizontal, vertical and oblique scanning directions. SOLUTION: A timing controller 17 controls the exposure timing of a CCD camera 6 to obtain beam detection information by detecting a scan beam 2 over a two-dimensional area. A synchronization detecting PD 5 detects synchronization information of a scan beam 2 to generate a synchronizing signal and count this signal, and the timing controller 17 actuates an LD 1 being a light source for the beam 2 to turn on/off according to the value of counts of the synchronizing signal. An image processor 14 calculates beam measurement information including at least any of the beam shape, the beam position and the beam-to-beam distance, based on the beam detection information of the beam 2 scanned by a plurality of adjacent polarization planes of a rotary polygonal mirror 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical system inspection device for a scanning writing optical system unit used in copying machines, printer products and the like, and more particularly to a beam for measuring a scanning beam of the scanning optical system. The present invention relates to a measuring device and its method.

[0002]

2. Description of the Related Art For inspection of a light beam emitted by a writing optical system used in a copying machine, a printer or the like, a P
The light emission timing of the LD (laser diode) and the CCD (charge coupled device) based on the synchronization signal detected by the D (photodetector using a photodiode or the like)
A method of determining the image pickup timing of the light receiving device represented by the above and acquiring the beam profile of the light beam is implemented. At this time, in order to remove an error component due to the dark current of the light receiving device, a dark current component table for each pixel is created by previously capturing an image with the shutter closed, and the dark current component table may be subtracted from the measured value. It is being appreciated. Also, from this result, 1 / e ² and 1 / e of the peak
e, or a region having a light intensity distribution of 1/2 or more is treated as the effective diameter of the light beam, and the intensity distribution profile is set to 2
A method of visually recognizing beam information by a three-dimensional or three-dimensional display method is also implemented. In recent years, in order to shorten the image forming time, a method of writing a plurality of scanning lines in a single scanning using a plurality of LDs, and a development of a small beam and a narrow pitch for improving the resolution have been progressing day by day. . As the precision of these image forming apparatuses increases, the performance required for the inspection apparatuses is also increasing, and the demand for inspection apparatuses that determine the quality of the image forming apparatus with fewer steps is also increasing.

One of the important factors required for these inspection devices is to measure the scanning beam in a state closer to the actual machine.
There is a function that can be inspected. For example, the scanning beam has a longer diameter in the main scanning direction than the stationary beam, but when focusing on one pixel, the charge storage time is shortened, that is, the charge storage amount is reduced. There is also a phenomenon that the beam diameter in the sub-scanning direction becomes small. As described above, there is a demand for a beam measuring apparatus and method for a scanning beam, which is capable of measuring and inspecting the shape of the scanning beam with high accuracy. For example, JP-A-9
JP-A-33390 discloses a scanning optical system based on a result obtained by copying scanning beam data for one line acquired by an area sensor in a sub-scanning direction, and calculating a difference between a two-dimensional image and a master image. A scanning optical system evaluation device for evaluation is disclosed.

[0004]

In an image forming apparatus such as a laser beam printer or a copying machine, in order to improve image quality and shorten printing time, the resolution is increased by reducing the diameter of the beam, and the rotation speed of a polygon mirror, that is, a rotary polygon mirror. Faster,
Also, multi-beaming and the like are being performed. With this,
The performance required for the inspection device for the writing optical system, which is the central part of these image forming apparatuses, is increasing year by year. One of the important conditions to be met when making this measurement is
"Measure in a state closer to the actual machine" can be mentioned. That is, for example, the beam position deviation in the main scanning direction and the beam diameter fluctuation due to the rotation unevenness of the rotary polygon mirror, and the beam position deviation for each scanning line due to the surface tilt are large measurement items that cannot be ignored. Such beam position deviation is
By overlapping the intensity distributions of the beam dots adjacent to each other in the main scanning direction, the sub scanning direction, and the diagonal direction, the influence on the image quality becomes stronger. In recent years, the beam size has been reduced as described above, and the beam interval has been narrowed accordingly. Therefore, it is necessary to measure the beam profile in the same state as the actual machine, including the influence of these adjacent beams.

In the above-mentioned Japanese Patent Laid-Open No. 9-33390, a writing unit is created by copying scanning beam data for one line in the sub-scanning direction and comparing the synthesized pseudo two-dimensional image data with the master image. It is shown that the pass / fail judgment is made. This inspection method can be expected to have some effect when the object is a single fθ lens, but when it is mounted on an actual machine, there are fluctuation factors such as the surface accuracy and surface tilt of the rotary polygon mirror, and there is one line worth. It cannot be said that the data does not always coincide with the scanning line by another deflecting surface. The present invention has been made in view of the above circumstances, and scanning in a state closer to an actual machine in consideration of overlapping of beam intensity distributions with adjacent dots not only in the main scanning direction but also in the sub-scanning direction and the diagonal direction. It is an object of the present invention to provide a scanning beam measuring apparatus and a method capable of measuring a beam. As described above, in image forming apparatuses such as printers and copiers, in order to improve image quality, the diameter of writing beams and the pitch between beams are becoming narrower. As a result, the specifications required for scanning beam measurement / inspection equipment have become higher year by year, and the beam in the same state as the actual machine, including the effect of the overlap of the intensity distribution with adjacent beams on the beam diameter and beam irradiation position The need for measuring profiles is emerging.

However, the conventional beam measuring apparatus only measures the beam profile for one scanning, and does not consider overlapping with the adjacent beams in the sub-scanning direction. As disclosed in Japanese Patent Laid-Open No. 9-33390, there is also proposed an apparatus that transfers a beam profile for one scanning in the sub-scanning direction, adds these, and measures the beam shape. However, the shape and irradiation position of the beam scanned by each deflecting surface of the rotary polygon mirror differ due to the influence of jitter or the like due to surface tilt or uneven rotation.
Therefore, it cannot be said that the beam information equivalent to the actual machine is obtained by the method of transferring the profile for one scan and combining the images. When measuring the scanning beam, the beam scanned by the deflecting surface that is scanning the beam to be measured and the adjacent deflecting surface are also measured, and based on the obtained data, not only the main scanning direction but also the sub-scanning direction and the oblique direction are measured. It is considered that the scanning beam can be measured in a state closer to the actual machine by calculating the beam shape, the beam position, the inter-beam distance, etc., in consideration of the overlap with the beams adjacent in the direction.

Therefore, an object of claim 1 of the present invention is to provide a scanning beam in a state closer to that of an actual machine in consideration of overlapping with adjacent beams not only in the main scanning direction but also in the sub-scanning direction and the oblique direction. An object is to provide a scanning beam measuring device capable of measuring. In addition, the scanning beam data by the continuous deflection surface detected by the light receiving device is sequentially stored, and the beam shape, position, inter-beam distance, etc. are obtained from the image information obtained by combining these data after the measurement of a predetermined scanning beam is completed. By calculating, it is possible to relatively easily measure the scanning beam in a state closer to the actual machine, in consideration of overlapping with adjacent beams in the sub-scanning direction and the diagonal direction as well as in the main scanning direction. Conceivable. Therefore, the object of claim 2 of the present invention is
A scanning beam measuring device capable of relatively easily measuring a scanning beam in a state closer to that of an actual machine in consideration of overlapping with adjacent beams not only in the main scanning direction but also in the sub-scanning direction and the diagonal direction. To provide.

Further, by moving the light receiving device relatively in the sub-scanning direction by a distance equal to the beam pitch while the deflection surface for scanning the beam is switched, the intensity distribution of the adjacent beams in the sub-scanning direction and the oblique direction can be obtained. It is considered that the beam measurement can be efficiently performed in a state close to the actual machine including the influence. That is, the object of claim 3 of the present invention is, in particular, to perform a scanning beam measurement in a state close to that of an actual machine including the influence of the intensity distributions of the beams adjacent in the sub-scanning direction and the oblique direction. It is to provide a beam measuring device. The beam scanning speed is very high, and it is difficult to transfer the beam information detected by the light receiving device to the memory or the like in accordance with the switching of the deflection surface of the rotating polygon mirror. A high-speed and high-performance light receiving device is required.
However, if the deflection surface and the image height are the same, the shape of the scanning beam is the same. Therefore, the scanning beam to be measured does not necessarily need to be continuous in time series as long as the deflection surfaces are adjacent to each other.

Therefore, for example, when measuring the scanning beam by the continuous first and second deflecting surfaces, exposure is performed while the detected information is transferred to the memory after the measurement of the scanning beam by the first deflecting surface is completed. By not controlling the exposure timing of the light receiving device so that the second deflecting surface is selected and the exposure is started after the transfer is completed, the light receiving device does not have to have high speed and high performance. It is believed that scanning beam measurements can be made. Therefore, it is an object of claim 4 of the present invention to provide a scanning beam measuring apparatus capable of measuring a scanning beam in a state similar to that of an actual machine, even if the light receiving device does not have high speed and high performance. . As described above, the scanning speed of the beam is very high, and it is difficult to move the light receiving device following the continuous switching of the deflecting surfaces of the rotary polygon mirror, and it is expensive to manufacture such a device. Costly. However, as described above, as long as the deflection surfaces of the scanning beams are adjacent to each other, they need not be continuous in time series.

Therefore, for example, consecutive first and second
When the beam scanned by the deflecting surface is measured, the light source is turned off after the measurement of the scanning beam by the first deflecting surface is completed (however, in order to always identify the deflecting surface, a passing period such as PD for synchronization detection is used. Before and after, the light source is temporarily turned on and turned on, and during this time, the light receiving device is relatively moved in the sub-scanning direction to perform positioning. After the positioning is completed, if the second deflecting surface is selected and the light source is turned on again to control the light source so that the beam is scanned,
It is considered that the scanning beam can be measured relatively inexpensively in the same state as the actual machine. Therefore, it is an object of claim 5 of the present invention to provide a scanning beam measuring apparatus capable of measuring a scanning beam in a state similar to that of an actual machine at a relatively low cost. Furthermore, it is considered that efficient measurement of all the scanning beams can be performed by performing the scanning beam measurement in the same state as the actual apparatus as described above for all image heights.

That is, an object of claim 6 of the present invention is to provide a scanning beam measuring apparatus capable of efficiently measuring the scanning beam in a state similar to that of an actual machine, for all the scanning beams. is there. Furthermore, when measuring the scanning beam, the beam scanned by the deflection surface adjacent to the deflection surface scanning the beam to be measured is also measured,
Based on the obtained data, considering the overlap with adjacent beams not only in the main-scanning direction but also in the sub-scanning direction and diagonal direction It is considered that the scanning beam can be measured in a state close to. Therefore, an object of claim 7 of the present invention is to measure the scanning beam in a state closer to the actual machine, in particular considering the overlap with adjacent beams in the sub-scanning direction and in the sub-scanning direction as well as in the main scanning direction. It is an object of the present invention to provide a scanning beam measuring method that enables the above. In addition, by moving the light receiving device relatively in the sub-scanning direction by a distance equal to the beam pitch while the deflection surface that scans the beam is switched, the intensity distribution of the adjacent beams in the sub-scanning direction and the diagonal direction can be determined. It is considered that the scanning beam can be efficiently measured in a state close to the actual machine including the influence.

That is, an object of claim 8 of the present invention is to measure a scanning beam efficiently, particularly in a state close to an actual machine including the influence of the intensity distribution of beams adjacent in the sub-scanning direction and the oblique direction. An object of the present invention is to provide a scanning beam measuring method that enables the scanning beam. Further, the scanning speed of the beam is very high, and a large amount of cost is required to transfer the beam information detected by the light receiving device to the memory or the like in accordance with the switching of the deflection surface of the rotary polygon mirror. However, if the deflection surface and the image height are the same, the shape of the scanning beam is the same. Therefore, the scanning beam to be measured does not necessarily need to be continuous in time series as long as the deflection surfaces are adjacent to each other. Therefore, for example, when measuring the scanning beam by the continuous first and second deflection surfaces, exposure is performed while the detected information is transferred to the memory after the measurement of the scanning beam by the first deflection surface is completed. However, if the exposure timing of the light receiving device is controlled so that the second deflecting surface is selected and the exposure is started after this transfer is completed, a scanning beam can be obtained in a state similar to that of an actual machine without requiring a large amount of cost. It is believed that can be measured. Therefore, it is an object of claim 9 of the present invention to provide a scanning beam measuring method which makes it possible to measure a scanning beam in a state similar to that of an actual machine, at a relatively low cost.

As described above, the beam scanning speed is very high, and a large amount of cost is required to manufacture an apparatus that moves the light receiving device in accordance with the switching of the continuous deflecting surfaces of the rotary polygon mirror. However, as described above, as long as the deflection surfaces of the scanning beams are adjacent to each other, they need not be continuous in time series. Therefore, for example, when measuring the beam scanned by the continuous first and second deflecting surfaces, after the measurement of the scanning beam by the first deflecting surface is completed, a period other than before and after the scanning beam detection period for synchronization detection is detected. The light source is turned off during the scanning period, the light receiving device is relatively moved in the sub-scanning direction during this time to perform positioning, and after the positioning is completed, the second deflecting surface is selected and the beam scanning is performed again. It is considered that the scanning beam can be measured in a state similar to that of an actual machine at a relatively low cost by controlling the. Therefore, it is an object of claim 10 of the present invention to provide a scanning beam measuring method which makes it possible to measure a scanning beam in a state similar to that of an actual machine at a relatively low cost.

[0014]

In order to achieve the above-mentioned object, a scanning beam measuring apparatus according to the present invention comprises a scanning optical system for deflecting and scanning a light beam by a rotary polygon mirror. A scanning beam measuring device for measuring a scanning beam in the scanning optical system of an image forming apparatus, which has a two-dimensional detection area, and light detection means for detecting the scanning beam to obtain beam detection information. Exposure timing control means for controlling the exposure timing of the light detection means, synchronization detection means for detecting synchronization information of the scanning beam and generating a synchronization signal, and counting the synchronization signals of the synchronization detection means. Counting means,
A synchronization signal generating means for generating a synchronization signal according to the count value of the counting means and a light source of the scanning beam are turned on / off.
Beam measurement including at least one of a beam shape, a position, and a beam-to-beam distance based on beam detection information of the scanning beam scanned by a plurality of deflection surfaces of the rotary polygon mirror that are turned off It is characterized by comprising an arithmetic means for calculating information.

According to a second aspect of the present invention, there is provided a scanning beam measuring apparatus which stores the beam detection information based on the light information detected by the light detecting means, and the storage holding means. An image synthesizing unit for synthesizing the image of a plurality of stored beam detection information is provided, and the image synthesizing unit stores a scanning beam by a plurality of continuous deflection surfaces of the rotary polygon mirror stored in the storage holding unit. A beam shape of the scanning beam, a position of the scanning beam, based on the combined image information obtained by the image combining means;
And a means for calculating beam measurement information including at least one of the inter-beam distances.

According to a third aspect of the present invention, there is provided a scanning beam measuring apparatus including a movement control means for controlling movement of the photodetection means in a sub-scanning direction within a scanning region of the scanning beam, and the movement control. The means includes means for relatively positioning and controlling the light detecting means in the sub-scanning direction in accordance with the deflecting surface of the rotary polygon mirror irradiated with the scanning beam, and the exposure timing control means is a plurality of predetermined plurality. It is characterized in that it includes means for continuing to expose the light detecting means while receiving the scanning beam by the deflecting surface. In the scanning beam measuring apparatus according to the present invention as set forth in claim 4, the exposure timing control means determines the first scanning beam of the first and second continuous deflection surfaces detected by the light detecting means. The light detection is performed so that the scanning of the scanning beam scanned by the second deflecting surface is performed after the scanning of the scanning beam by the deflecting surface is completed and the detected optical information is completely transferred to the storage holding means. It is characterized by including means for controlling the exposure timing of the means.

According to a fifth aspect of the present invention, there is provided a scanning beam measuring apparatus according to the present invention, wherein the light source modulating means has the first and second scanning beams which are successively detected by the light detecting means. Means for modulating the light source so as to perform scanning detection of the scanning beam scanned by the second deflecting surface after the scanning of the scanning beam by the first deflecting surface is completed and the positioning in the sub-scanning direction is completed. It is characterized by including. The scanning beam measuring apparatus according to the present invention according to claim 6 comprises means for moving the light detecting means also in the main scanning direction, and beam measurement is sequentially performed in the entire scanning area of the image forming apparatus. I am trying. Further, in order to achieve the above-mentioned object, the scanning beam measuring method according to the present invention as set forth in claim 7 is an image forming apparatus having a scanning optical system that deflects and scans a light beam by a rotating polygon mirror. A scanning beam measuring method for measuring a scanning beam in an optical system, comprising: a first step of detecting a scanning beam by a plurality of continuous deflecting surfaces of the rotary polygon mirror by a light detecting means to obtain beam detection information. And a second step of calculating beam measurement information including at least one of the scanning beam shape, position, and beam-to-beam distance based on the plurality of beam detection information obtained in the first step. It is characterized by that.

In the scanning beam measuring method according to the present invention described in claim 8, in the first step, the light detecting means is moved in the sub-scanning direction in accordance with a deflecting surface which is irradiated with the scanning beam. It is characterized in that it includes a step of performing. The scanning beam measuring method according to the present invention as set forth in claim 9,
The scanning beam by the continuous first and second deflecting surfaces obtained in the first step has been scanned by the first deflecting surface, and the detected beam detection information is stored in the storage unit. It is characterized by including a third step of controlling the exposure timing so that the scanning beam scanned by the second deflecting surface is detected after the transfer is completed. In the scanning beam measuring method according to the present invention as set forth in claim 10, the scanning beam by the continuous first and second deflecting surfaces detected in the first step is scanned by the first deflecting surface. And the positioning in the sub-scanning direction is completed, the third step of controlling the modulation timing of the light source of the scanning beam so that the scanning beam scanned by the second deflecting surface is detected. It is characterized by including.

[0019]

That is, the scanning beam measuring apparatus according to claim 1 of the present invention is for measuring the scanning beam in the scanning optical system of the image forming apparatus having the scanning optical system for deflecting and scanning the light beam by the rotary polygon mirror. In the scanning beam measuring apparatus, the exposure timing control means controls the exposure timing of the light detection means for detecting the scanning beam having two-dimensional detection areas to obtain beam detection information, and the synchronization detection means performs the scanning. The synchronization information of the beam is detected to generate a synchronization signal, the synchronization signal of the synchronization detection means is counted by the counting means, and the synchronization signal is generated by the synchronization signal generation means according to the count value of the counting means. The light source of the scanning beam is turned on / off by the light source modulating means, and the computing means is provided with a plurality of adjacent deflection surfaces of the rotary polygon mirror. Therefore beam shape on the basis of the beam information detected by the scanning beams scanned, it calculates the position, and the beam measurement information including at least one of the beam distance. With such a configuration, it is possible to measure the scanning beam in a state closer to that of the actual machine, particularly in consideration of overlapping with adjacent beams in the sub-scanning direction and the oblique direction as well as in the main scanning direction.

According to a second aspect of the present invention, there is provided a scanning beam measuring apparatus which stores and holds beam detection information based on the light information detected by the light detection means and a plurality of storage means. Image synthesizing means for synthesizing the image of the beam detection information of the above, and the image synthesizing means synthesizes the beam detection information of the scanning beam by the plurality of continuous deflection surfaces of the rotary polygon mirror stored in the storage holding means. Means for calculating the beam measurement information including at least one of the beam shape, the position, and the inter-beam distance of the scanning beam, based on the combined image information obtained by the image combining means. Including means for calculating. With such a configuration,
It is possible to relatively easily perform the measurement of the scanning beam in a state closer to the actual machine, considering the overlap with the adjacent beams in the sub-scanning direction and the oblique direction as well as in the main scanning direction.

A scanning beam measuring apparatus according to a third aspect of the present invention comprises a movement control means for controlling movement of the light detecting means in a sub-scanning direction within a scanning region of the scanning beam, and the movement control means comprises: The exposure timing control means includes means for relatively positioning the light detection means in the sub-scanning direction according to the deflection surface of the rotary polygon mirror irradiated with the scanning beam. Means for continuing to expose the light detecting means while receiving the scanning beam. With such a configuration, it is possible to efficiently perform the scanning beam measurement particularly in a state close to the actual machine, including the influence of the intensity distribution of the adjacent beams in the sub-scanning direction and the oblique direction. In the scanning beam measuring apparatus according to the fourth aspect of the present invention, the exposure timing control means includes the first and second continuous light detection means which are detected by the light detection means.
Scanning of the scanning beam by the first deflecting surface, scanning of the scanning beam by the first deflecting surface is completed, and after the detected optical information is completely transferred to the memory holding means, scanning by the second deflecting surface is performed. A means for controlling the exposure timing of the light detecting means is included so as to perform scanning detection of the beam. With such a configuration, even if the light receiving device does not have high speed and high performance, the scanning beam can be measured in the same state as in the actual machine.

According to a fifth aspect of the present invention, in the scanning beam measuring apparatus, the light source modulation means performs the first deflection on the scanning beam by the continuous first and second deflection surfaces detected by the light detection means. Means for modulating the light source to perform scan detection of the scanning beam scanned by the second deflecting surface after finishing scanning the scanning beam by the surface and completing positioning in the sub-scanning direction. With such a configuration, it is possible to measure the scanning beam in a state similar to that of an actual machine at a relatively low cost. A scanning beam measuring device according to claim 6 of the present invention comprises:
A means for moving the light detecting means also in the main scanning direction is provided, and beam measurement is sequentially performed in the entire scanning area of the image forming apparatus. With such a configuration, in particular, the scanning beam measurement in the same state as the actual apparatus can be efficiently performed for all scanning beams.

Further, a scanning beam measuring method according to a seventh aspect of the present invention is for measuring a scanning beam in the scanning optical system of an image forming apparatus having a scanning optical system for deflecting and scanning a light beam by a rotary polygon mirror. The method for measuring a scanning beam according to claim 1, wherein the scanning beam by the plurality of continuous deflection surfaces of the rotary polygon mirror is detected by the photodetector to obtain beam detection information, and the beam is acquired by the first step. And a second step of calculating beam measurement information including at least one of the scanning beam shape, position, and inter-beam distance based on the plurality of pieces of beam detection information. By doing so, it becomes possible to measure the scanning beam in a state closer to that of the actual machine, in particular considering the overlap with the adjacent beams in the sub-scanning direction and the diagonal direction as well as in the main scanning direction. Claim 8 of the present invention
In the scanning beam measuring method according to, the first step includes a step of moving the photodetection means in the sub-scanning direction in accordance with the deflecting surface irradiated with the scanning beam. By doing so, it becomes possible to efficiently measure the scanning beam particularly in a state close to the actual machine including the influence of the intensity distribution of the beams adjacent in the sub-scanning direction and the oblique direction.

In the scanning beam measuring method according to claim 9 of the present invention, the scanning beam by the continuous first and second deflecting surfaces obtained in the first step is the scanning beam by the first deflecting surface. After the scanning is completed and the detected beam detection information is transferred to the memory holding means, the scanning beam scanned by the second deflecting surface is detected.
The third step of controlling the exposure timing is included. By doing so, it becomes possible to measure the scanning beam in a state similar to that of an actual machine, particularly at a relatively low cost. In the scanning beam measuring method according to claim 10 of the present invention, the scanning beam by the continuous first and second deflection surfaces detected in the first step is completed when the scanning by the first deflection surface is completed. And a third step of controlling the modulation timing of the light source of the scanning beam so that the scanning beam scanned by the second deflecting surface is detected after the positioning in the sub-scanning direction is completed. By doing so, it becomes possible to measure the scanning beam in a state similar to that of an actual machine at a relatively low cost.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The scanning beam measuring apparatus and method of the present invention will be described in detail below with reference to the drawings based on the embodiments. 1 to 6 are for explaining the configuration and operation of the scanning beam measuring apparatus according to the first embodiment of the present invention. FIG. 1 is a schematic diagram showing a configuration of a main part of a scanning beam measuring apparatus according to a first embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation of the scanning beam measuring apparatus, and FIG. FIG. 4 is a schematic view for explaining the operation of the scanning beam measuring apparatus, FIG. 4 and FIG.
FIG. 6 is a schematic diagram for explaining the operation of the scanning beam measuring device, and FIG. 6 is a block diagram showing in detail the configuration of part of the scanning beam measuring device. The scanning beam measuring apparatus shown in FIG. 1 includes an LD (laser diode) unit 1, a rotary polygon mirror (polygon mirror) 3, a lens group 4, and a synchronous detection P.
D (photodetector) 5, two-dimensional area CCD (charge coupled device) camera 6, host PC (personal computer) 13, image calculation unit 14, stage controller 15, LD controller 16, CCD exposure control unit 19,
Main scanning direction stage 21 and sub scanning direction stage 2
Equipped with 2.

An LD unit 1 composed of one or more LDs is a light source for generating a scanning beam 2, and the scanning beam 2 is deflected by a rotary polygon mirror 3 and a lens group 4 constituting a scanning optical system. Let the scan take place. PD5 for synchronization detection
Is a synchronization detecting means, which detects the scanning beam 2 at the edge of the deflection scanning range and obtains synchronization information of beam scanning. The LD unit 1, the rotary polygon mirror 3, the lens group 4, the synchronization detection PD 5 and the like constitute the writing unit 10. A two-dimensional area type CCD camera 6 is used as a photodetector having a two-dimensional detection area and detecting the scanning beam 2 to obtain beam detection information. The host PC 13 controls the operation of the scanning beam measuring apparatus, and calculates the beam measuring information including at least one of the beam shape, the position, and the inter-beam distance based on the beam detection information of the scanning beam 2. Image calculation unit 14 including means, and the two-dimensional area CCD
The stage controller 15 that controls the movement of the camera 6 is controlled by the host PC 13. LD controller 16 for controlling LD unit 1 and two-dimensional area type CC
A timing control unit 17 is configured with the CCD exposure control unit 19 that controls the exposure of the D camera 6. The timing control unit 17 is an exposure timing control unit for controlling the exposure timing of the two-dimensional area CCD camera 6, a synchronization signal generation unit for generating a synchronization signal, and the LD unit 1.
It also functions as a light source modulation means for turning on / off. The main scanning direction stage 21 and the sub scanning direction stage 22 are two-dimensional area type C when measuring the scanning beam 2.
A mechanism for moving the CD camera 6 is configured.

In FIG. 1, the writing unit 10 is L
The scanning beam 2 emitted from the D section 1 is deflected by the rotary polygon mirror 3, passes through the lens group 4, and forms an image on the image plane.
An apparatus for inspecting such a writing unit 10 is the scanning beam measuring apparatus according to the present invention, which is used to detect the imaging timing of the two-dimensional area CCD camera 6 arranged on the image plane and the modulation of the LD unit 1. , Control is performed based on a signal from the synchronization detection PD 5. The host PC 13 controls the positioning of the CCD camera 6 via the stage controller 15 and obtains beam information such as the beam diameter, the beam position, and the inter-beam distance from the beam image measured by the CCD camera 6, and performs the required processing. Give. The writing unit 10 is, as shown in FIG.
After detecting the rising edge of the output signal (time t1 in FIG. 2), the H (high level) / L (low level) of the LD control signal is controlled so that the scanning beam 2 is irradiated at a predetermined position. , LD section 1 is on / off modulated.
After repeating this modulation control with a preset pattern,
The LD unit 1 is once turned off. In order to irradiate the synchronization detection PD 5 with the scanning beam 2 scanned by the polygon mirror, that is, the deflecting surface next to the rotary polygon mirror 3, the timing after passing through a predetermined writing area (see FIG. 2).
At time t6), the LD unit 1 is turned on again and is subjected to ON / OFF modulation control. By repeating such an operation, beam scanning is performed by each deflecting surface of the rotary polygon mirror 3.

The CCD camera 6 is triggered by the rising edge of the output signal of the PD 5 for synchronization detection,
After a certain time (time t2 in FIG. 2), the CCD reset signal falls so as to reset the electric charge stored in the CCD camera 6. After that, the exposure is started by being triggered by the rising edge of the CCD exposure signal a certain time before the lighting of the LD unit 1 (time t3 in FIG. 2), and the beam scanning in the scanning region ends (time t4 in FIG. 2). After a certain time (Fig. 2
At time t5), the timing is controlled so that the exposure is completed at the falling edge of the CCD exposure signal. The scanning beam is measured by transferring the optical information photoelectrically converted during the exposure period to the image calculation unit 14 or the memory. As already mentioned, such a writing unit 10
In recent years, beam reduction and narrowing of pitch have been progressing rapidly, and in order to measure the beam shape and beam position, which have a large effect on image quality, with high accuracy, the overlap of the light intensity distribution with adjacent dots It is necessary to make a proper consideration for the measurement.

For example, a six-sided polygon mirror is a rotary polygon mirror 3
When the scanning beam 2 by each deflecting surface is observed on the surface of the photoconductor when the beam scanning is performed as shown in FIG.
As shown in. In Figure 3, the numbers circled are
The deflection planes of the rotary polygon mirror 3 and the correspondence between these deflection planes and the beam spot array are shown. At this time, for example, if the rotary polygon mirror 3 has jitter or surface tilt, the distance between dots varies in the main scanning direction and the sub-scanning direction, as in the scanning beam spot indicated by the diagonal lines in the figure. Of course, it cannot be said that there is no effect on the beam diameter, and variations in these beams cause streaks and uneven density in the printed image, leading to image quality degradation. Need to measure and inspect. At this time, as shown in FIG. 4, when there are adjacent beams in the sub-scanning direction and the pitch of the beam spot becomes narrower as compared with the case of only one scanning, as shown in FIG. Since the intensity distributions of the light amounts of the dots adjacent to each other in the oblique direction overlap with each other and the beam diameter is also strongly affected, it is necessary to take these into consideration when performing the measurement. However, the conventional scanning beam measuring device and measuring method do not consider these factors and merely measure the beam shape for each scanning line. An apparatus has also been proposed in which a scanning beam for one scanning is measured and transferred in the sub-scanning direction and synthesized, but this apparatus does not consider the characteristics of each deflecting surface in the rotary polygon mirror, and for example, one surface is used. Even if there is a defect in the scanning optical system, if the result of measuring the other surface meets the given specifications, the scanning optical system is determined to be a good product.
Therefore, for example, as shown in FIG.
7, a programmable counter 18 is provided so as to be controlled by the host PC 13. The timing control unit 17 counts the signal from the PD 5 for synchronization detection by using the programmable counter 18, and specifies which deflecting surface of the rotary polygon mirror 3 is scanning the currently scanned beam. The LD unit 1 according to this count value
Lighting, the exposure timing of the CCD camera 6, and C
By controlling the movement of the CD camera 6 or the like, it is possible to measure a predetermined plurality of continuous scanning lines. From these results, the beam shape, beam position, inter-beam distance, etc. are calculated, and the sub-scanning direction or diagonal direction is calculated. It is possible to measure a scanning beam shape that is more equivalent to the actual machine, including the influence of the light intensity distribution of the dots adjacent to.

According to the above-mentioned scanning beam measuring apparatus, it is possible to measure the scanning beam profile in a state closer to the actual machine, including the influence of the adjacent beams in the sub-scanning direction and the oblique direction. In addition, it is possible to individually specify a plurality of deflecting surfaces of the rotary polygon mirror 3 and measure the scanning beam, and thereby it is possible to measure the performance of the rotary polygon mirror 3 such as surface tilt. Yes (the above corresponds to claim 1). The block diagram of FIG. 7 shows a configuration of a main part of a scanning beam measuring apparatus according to a second embodiment of the present invention. In the configuration shown in FIG. 7, the memory 20 and the image composition unit 25 are serially inserted between the CCD camera 6 and the image calculation unit 14. The memory 20 as a storage holding unit stores and holds the beam detection information based on the light information detected by the CCD camera 6 which is the light detection unit. The image synthesizing unit 25 as an image synthesizing unit imagewise synthesizes the plurality of beam detection information stored in the memory 20. The image synthesizing unit 25 has a function of synthesizing the beam detection information of the scanning beams stored in the memory 20 by the plurality of continuous deflection surfaces of the rotary polygon mirror 3.

The image calculation section 14 as a calculation means.
Has a function of calculating beam measurement information including at least one of the beam shape, position, and inter-beam distance of the scanning beam 2 based on the combined image information obtained by the image combining unit 25. In such a configuration, CC
The D camera 6 sequentially transfers and stores the beam information deflected and scanned by the required plurality of deflection surfaces to the memory 20 for storing the photoelectrically converted light information. After the measurement of all the scanning beams, the image synthesizing section 25 shifts the beam information stored in the memory 20 by a predetermined distance in the sub-scanning direction, that is, a distance equal to the beam pitch, and then synthesizes the image. The image calculation unit 14 calculates each beam shape, beam position, inter-beam distance, and the like, based on the combined image obtained by the image combining unit 25. In this way, it is possible to measure the scanning beam in a state equivalent to that of the actual machine, as in the case of the first embodiment. Therefore, considering the influence of adjacent beams in the sub-scanning direction and the diagonal direction,
It is possible to measure a beam profile that is more faithful to the actual machine. Further, since the beam is applied to a substantially constant area of the light receiving device, the effect of reducing the measurement error due to the variation in the sensitivity of each pixel can be obtained (the above corresponds to claim 2).

By the way, the speed of the scanning beam is high, and the transfer of the data acquired by the CCD camera 6 may not be completed within the time when the deflecting surface is switched. Therefore, in the third embodiment of the present invention,
The stage controller 15 as a movement control means controls the movement of the CCD camera 6 in the sub-scanning direction within the scanning area of the scanning beam 2, and the stage controller 15 causes the deflection surface of the rotary polygon mirror 3 to be irradiated with the scanning beam. According to the position of the CCD camera 6 in the sub-scanning direction.
7 has a function of continuously exposing the CCD camera 6 while receiving the scanning beam 2 formed by a plurality of predetermined deflecting surfaces. For example, as in the pattern of beam spots shown in FIG. 8, when measuring the scanning beam 2 by the continuous deflection surface, different regions of the CCD camera 6 for each scanning beam line, that is, the beam line pitch in the sub-scanning direction in the actual machine. The CCD camera 6 and the writing unit 10 are relatively moved in the sub-scanning direction so that the beam is displaced by a distance equal to L. At this time, as shown in the timing chart of FIG. 9, the CCD camera 6 is continuously exposed until the scanning beams 2 on all six surfaces are received, and then the timing is controlled so that the beam shape is calculated.

By doing so, the scanning beam for each deflecting surface is irradiated onto the CCD camera 6 in a state similar to that of an actual machine, and the light intensity distribution of dots adjacent in the sub-scanning direction and the diagonal direction is also taken into consideration. It is possible to calculate the scanning beam shape corresponding to the actual machine. The circled numbers in FIG. 9 indicate the portions corresponding to the respective deflection surfaces of the rotary polygon mirror 3 shown in FIG. Therefore, even when the information reading speed of the CCD camera 6 is not sufficiently higher than the scanning speed of the beam, it is possible to measure the beam profile including the overlap with the adjacent beam as described above (the above are claimed). (Corresponding to item 3). Further, the beam scanning speed in the writing unit 10 is very high,
It is difficult for the currently available CCD camera 6 to transfer the beam information detected in the memory 20 or the like in a short time while the deflection surface of the scanning beam 2 on the continuous deflection surface of the rotary polygon mirror 3 is switched. Is. However, if the deflection surface and the image height are the same, the shape of the scanning beam 2 is the same. Therefore, as long as the deflection surfaces of the scanning beam 2 are adjacent to each other, the measurement data collection is not necessarily continuous in time series. You don't have to be.

Therefore, in the fourth embodiment of the present invention, the timing control section 17 as the exposure timing control means controls the scanning beam 2 by the first and second deflection surfaces detected by the CCD camera 6 to After the scanning of the scanning beam 2 by the first deflecting surface is completed and the detected optical information is completely transferred to the memory 20 or the like as a memory holding unit, the scanning beam 2 scanned by the second deflecting surface is scanned. It has a function of controlling the exposure timing of the CCD camera 6 so that scanning detection is performed. That is, in the measurement of the scanning beam 2 by the continuous deflecting surface, for example, as shown in FIG. 10, (the circled numbers ~ in FIG. 10 indicate the positions corresponding to the respective deflecting surfaces of the rotary polygon mirror 3 shown in FIG. (Shown), the scanning beam by the deflection surface is CC
After exposing and measuring the D camera 6, the exposure signal of the CCD camera 6 is set to L (off) until the rise of the data transfer completion signal is confirmed. When the rise of the data transfer completion signal (time t1 in FIG. 10) is confirmed, the timing is controlled so that the CCD camera 6 is exposed again by being triggered by the synchronization detection signal by the deflecting surface (time t2 in FIG. 10). By sequentially repeating such control for each deflecting surface, it is possible to measure a scanning beam by continuous deflecting surfaces without using a high-speed compatible CCD camera, and to obtain an adjacent beam intensity distribution in the sub-scanning direction. It is possible to measure the scanning beam in the same condition as the actual machine, considering it.

Therefore, it is possible to measure the scanning beam by the continuous deflecting surface without using the CCD camera 6 as the light detecting means having a high-speed light detecting function, and to measure the beam shape in the same state as in the actual machine ( The above corresponds to claim 4. The beam scanning speed of the writing unit 10 is very high, and in order to measure the scanning beam by the continuous deflecting surface of the rotary polygon mirror 3, the CCD camera 6 as the light detecting means is moved following the switching of the deflecting surface. It is difficult to make a control system, and in order to achieve it, a highly accurate mechanism and a high performance controller are required. However, as described above, the measurement timing does not necessarily need to be continuous in time series as long as the deflection surfaces of the scanning beam 2 are adjacent to each other. Therefore, in the fifth embodiment of the present invention, the LD controller 16 as the light source modulating means has the scanning beam 2 formed by the continuous first and second deflecting surfaces detected by the CCD camera 6 as the light detecting means. However, after the scanning of the scanning beam by the first deflecting surface is completed and the positioning in the sub-scanning direction is completed, scanning detection of the scanning beam scanned by the second deflecting surface is performed. Has a function of modulating the LD unit 1.

That is, in the measurement of the scanning beam by the continuous deflection surface, for example, as shown in FIG. 11, the CCD camera 6 is synchronized with the beam scanned by the deflection surface.
Exposure is started (time t1 in FIG. 11). After the scanning of the CCD camera 6 is completed, as shown in FIG.
And the writing unit 10 are relatively moved in the sub-scanning direction by a distance L equal to the inter-dot distance. Until this movement is completed, the LD unit 1 is only incident on the synchronization detection PD 5.
Modulation control is performed so that lights up and lights off other than. After confirming the movement completion signal (time t2 in FIG. 11), the synchronization detection signal is triggered to control the lighting timing of the LD unit 1 of the light source so that the deflection surface scans the beam, and the CCD camera 6 is turned on. Set to the exposure state. By sequentially performing such an operation for each deflecting surface, it is possible to realize the same condition as the actual machine, considering the adjacent beam intensity distribution in the sub-scanning direction without using the mechanism and control system that can move and position at high speed. It becomes possible to measure the scanning beam. Therefore, it is possible to measure the scanning beam 2 with a continuous deflecting surface without using a high-precision mechanism, a high-performance controller, and the CCD camera 6 as the light detecting means, and to measure the beam shape in a state similar to an actual machine. Yes (the above corresponds to claim 5).

Further, in the sixth embodiment of the present invention, the beam shape at any one image height is measured by using the mechanism and operation in the above-mentioned first to fifth embodiments, and Image height, for example, by the same length as the width of the CCD camera 6 in the main scanning direction, and beam measurement is performed in the same manner. By repeating this operation, it is possible to measure the scanning beam at the entire image height of the writing unit having a long scanning area in the main scanning direction. At this time, for example, one or more beams at the ends are moved so as to be measured in an overlapping manner, and the beams are measured at two image heights with the overlapping measured beams as a reference to offset the beam position. It may be configured to multiply by or to correct the inclination of the line connecting the center of gravity of the beam. Therefore, it is possible to measure the beam of the entire image height in the same state as the actual machine (the above corresponds to claim 6). As described above in connection with the first embodiment of the present invention, in order to measure the beam shape with high accuracy, the measurement should be performed in consideration of the overlap of the light intensity distribution with the adjacent dots. There is a need.

Therefore, a seventh embodiment of the present invention relates to a scanning beam measuring method, which is an image forming apparatus having a scanning optical system for deflecting and scanning a light beam by the rotary polygon mirror 3. A scanning beam measuring method for measuring a scanning beam in a scanning optical system is provided. The scanning beam measuring method includes a first step of detecting the scanning beam 2 by a plurality of continuous deflecting surfaces of the rotary polygon mirror 3 by a CCD camera 6 as a light detecting means to obtain beam detection information, respectively. A second step of calculating beam measurement information including at least one of the scanning beam shape, the position, and the inter-beam distance based on the plurality of beam detection information obtained in step 1. That is, for example, as shown in FIG.
The method of adjusting the lighting of the LD unit 1 and the exposure timing of the CCD camera 6 by specifying which deflection surface of the rotary polygon mirror 3 is scanning the beam currently being scanned by counting the signal from the. By using it, it is possible to measure a certain number of consecutive scanning lines, and calculate the beam shape, beam position, beam distance, etc. from these results to determine the light intensity of dots that are adjacent in the sub-scanning direction or diagonal direction. It becomes possible to measure the scanning beam shape more realistically, including the influence of the distribution.

Therefore, it is possible to measure the scanning beam profile in a state closer to the actual machine, including the influence of the adjacent beams in the sub-scanning direction and the oblique direction. There is also an advantage that the performance of the rotary polygon mirror 3 such as a surface tilt can be measured by specifying the deflection surface and measuring the scanning beam 2 (the above corresponds to claim 7). FIG. 12 shows a flowchart of the scanning beam measurement by the continuous deflection surface in the scanning beam measurement method according to the eighth embodiment of the present invention. That is, after the start of measurement,
The stage is moved to the measurement point in the sub-scanning direction (step S
11). The deflection surface is specified by counting the synchronization detection signal (step S12) (step S13), and the scanning beam image is captured (step S14). Next, if the scanning beam measurement of all the deflection surfaces has not been completed (step S15), the process returns to step S11, and the CCD camera 6 and the writing unit 10 are relatively moved in the sub-scanning direction by a distance equal to the pitch of the scanning beam lines. After moving, the desired deflecting surface is selected again based on the signal from the synchronization detection PD 5 and the scanning beam image is captured again. The above operation is repeated for the number of deflection surfaces of the rotary polygon mirror, and when the scanning beam measurement of all the deflection surfaces is completed, the beam shape, the beam position, the inter-beam distance, etc. are finally calculated by image calculation (step S16). By such a method, it becomes possible to measure the scanning beam shape in the same state as the actual machine. Therefore, even when the information transfer speed of the CCD camera 6 as the light detecting means is not sufficiently high with respect to the scanning speed of the beam, the beam profile including the overlap with the adjacent beam can be measured (the above is a request). (Corresponding to item 8). In the method according to the eighth embodiment described above, instead of using the moving mechanism, for example, the scanning beam by each deflection surface is individually measured, and finally each measurement image is shifted by the beam pitch in the sub-scanning direction. A method of performing correction and calculating a beam shape from an image obtained by combining the corrected images may be used. This is the scanning beam measuring method according to the ninth embodiment of the present invention. FIG. 13 shows a flowchart of the scanning beam measurement by the continuous deflection surface in the scanning beam measurement method according to the ninth embodiment of the present invention.

That is, after the start of measurement, the PD 5 for synchronization detection
The deflection surface is selected by counting the synchronization detection signal from (step S21 and step S22), and the scanning beam is captured (step S24). However, in the second and subsequent measurements, the next deflection surface adjacent to the previously measured deflection surface, that is, the deflection surface where the count value of the synchronization signal is (the number of deflection surfaces x an arbitrary integer + 1) compared to the previous measurement After selection (steps S21 to S23), exposure of the CCD camera 6 is started, and a scanning beam image is captured in step S24. The data thus measured is transferred to the memory 20 or the like (step S25), and after the transfer is completed, it is determined whether or not to measure the scanning beam by the next deflecting surface (step S26). If the measurement of the scanning beam by the desired deflection surface has not been completed, the above steps S21 to S are performed.
Deflection surface selection and beam capture as in 25 are repeated. When the measurement of all scanning beams is completed by repeating this method, the temporarily stored data is image-corrected so as to be shifted in the sub-scanning direction in the deflection plane order by the beam pitch, and the beam diameter is calculated from the data obtained by superimposing these images (step S27). Then, the position and the like are calculated (step S28), and the measurement ends.

Therefore, without using the CCD camera 6 as an expensive light detecting means capable of reading and transferring high-speed data, the scanning beam by the continuous deflecting surface is measured, and the beam shape in the same state as the actual machine is measured. It is possible (the above corresponds to claim 9). Next, FIG. 14 shows a flowchart of the scanning beam measurement by the continuous deflection surface in the scanning beam measurement method according to the tenth embodiment of the present invention. That is, after the measurement is started, the synchronization detection signal (step S31) is counted to identify the deflection surface (step S32), and the CCD camera 6 and the writing unit 10 are relatively moved to the measurement position in the sub-scanning direction (step). S33) (Although not clearly shown, the synchronization detection signal is continuously counted during the movement). After the movement is completed (step S34), the count value of the synchronization detection signal (step S35) is used (step S34).
36) It is judged whether or not it is a desired deflecting surface (step S
37) If the deflection surface is desired, the beam is turned on in a predetermined pattern (step S38), and scanning / exposure is performed (step S39). In step S37, if the deflection surface is not the desired deflection surface, the LD unit 1 does not light up and returns to step S35 to wait for the desired deflection surface.

Even if the LD unit 1 is not turned on, the beam from the next deflecting surface is incident on the PD 5 for synchronization detection.
After a predetermined time, that is, when the scanning beam passes through the writing area when the beam is turned on, the LD
The section 1 is set to light up. Step S39
After the scanning beam exposes the CCD camera 6, it is determined whether or not a predetermined total scanning beam measurement is completed (step S
40) If the total scanning beam measurement is not completed, the process returns to step S33 again, the CCD camera 6 and the writing unit are relatively moved, and steps S33 to S3 described above are performed.
The measurement of 9 is repeated, and if the total scanning beam measurement is completed in step S40, the exposure is completed, the beam diameter, the beam position, etc. are calculated from the obtained data (step S41), and the measurement is completed. Therefore, it is possible to measure a scanning beam by a continuous deflecting surface without using a high-precision mechanism or a high-performance controller, and to measure a beam shape in a state similar to that of an actual machine.
Corresponding to).

[0043]

As described above, according to the present invention, the overlap of the beam intensity distributions with the adjacent dots in the sub-scanning direction and the oblique direction as well as in the main scanning direction is taken into consideration.
It is possible to provide a scanning beam measuring apparatus and method that can measure a scanning beam in a state closer to an actual machine. That is, according to the scanning beam measuring apparatus of claim 1 of the present invention, for measuring the scanning beam in the scanning optical system of the image forming apparatus having the scanning optical system for deflecting and scanning the light beam by the rotary polygon mirror. In the scanning beam measuring device, the exposure timing control means controls the exposure timing of the light detecting means for detecting the scanning beam having two-dimensional detection areas to obtain beam detection information, and the synchronization detecting means controls the scanning beam. Detecting the synchronization information and generating a synchronization signal, counting the synchronization signal of the synchronization detecting means by a counting means, generating a synchronization signal by the synchronization signal generating means in accordance with the count value of the counting means, and scanning. The light source of the beam is turned on / off by the light source modulation means, and the arithmetic means operates by the plurality of adjacent deflection surfaces of the rotary polygon mirror. With the configuration for calculating the beam measurement information including at least one of the beam shape, the position, and the inter-beam distance on the basis of the beam detection information of the scanning beam to be scanned, not only the main scanning direction but also the sub-scanning direction and the oblique direction are obtained. The scanning beam can be measured in a state closer to the actual machine in consideration of overlapping with beams adjacent in the direction.

According to the scanning beam measuring apparatus of the second aspect of the present invention, the storage holding means for storing and holding the beam detection information based on the light information detected by the light detecting means, and the storage holding means. An image synthesizing unit for synthesizing the plurality of beam detection information thus obtained is provided, and the image synthesizing unit detects a beam of a scanning beam by a plurality of continuous deflection surfaces of the rotary polygon mirror stored in the storage holding unit. A beam including a unit for synthesizing information, and the arithmetic unit including at least one of a beam shape, a position, and an inter-beam distance of the scanning beam based on the synthesized image information obtained by the image synthesizing unit. By including the means for calculating the measurement information, the overlap with adjacent beams in the sub-scanning direction and the oblique direction as well as the main scanning direction is considered. Was, the more measurements of the scanning beam in a state close to the actual machine can be carried out relatively easily.
According to the scanning beam measuring apparatus of claim 3 of the present invention, the scanning beam measuring apparatus further comprises a movement control means for controlling the movement of the photodetection means in the sub-scanning direction within the scanning region of the scanning beam, and the movement control means comprises: The exposure timing control means includes means for relatively positioning the light detection means in the sub-scanning direction according to the deflection surface of the rotary polygon mirror irradiated with the scanning beam, and the exposure timing control means scans with a plurality of predetermined deflection surfaces. By including a means for continuing the exposure of the light detecting means while receiving the beam, it is possible to measure the scanning beam in a state close to an actual machine, including the influence of the intensity distribution of the adjacent beams in the sub-scanning direction and the oblique direction. It can be done efficiently.

According to the scanning beam measuring apparatus of the fourth aspect of the present invention, the exposure timing control means controls the scanning beam by the first and second continuous deflection surfaces detected by the photodetecting means. The scanning of the scanning beam scanned by the second deflecting surface is performed after the scanning of the scanning beam by the first deflecting surface is completed and the detected optical information is completely transferred to the memory holding means. By including the means for controlling the exposure timing of the light detection means, it is possible to measure the scanning beam in a state similar to that of an actual machine, even if the light receiving device does not have high speed and high performance. According to the scanning beam measuring apparatus of the fifth aspect of the present invention, the light source modulation means is configured to detect the scanning beam by the first and second deflection surfaces which are consecutive by the light detection means, by the first deflection surface. By including means for modulating the light source so as to perform scanning detection of the scanning beam scanned by the second deflecting surface after the scanning beam is scanned by and the positioning in the sub-scanning direction is completed. In particular, the measurement of the scanning beam in a state similar to that of the actual machine can be performed relatively inexpensively.

According to the scanning beam measuring apparatus of the sixth aspect of the present invention, it is provided with means for moving the light detecting means also in the main scanning direction, and the beam measurement is sequentially carried out in the entire scanning area of the image forming apparatus. With this, in particular, the measurement of the scanning beam in the same state as the actual apparatus can be efficiently performed for all the scanning beams. Further, according to the scanning beam measuring method of the seventh aspect of the present invention, for measuring the scanning beam in the scanning optical system of the image forming apparatus having the scanning optical system for deflecting and scanning the light beam by the rotary polygon mirror. A scanning beam measuring method, comprising: a first step of detecting a scanning beam by a plurality of continuous deflecting surfaces of the rotary polygon mirror by a light detecting means to obtain beam detection information, respectively;
And a second step of calculating beam measurement information including at least one of the scanning beam shape, position, and inter-beam distance based on the plurality of beam detection information obtained by the step of , In particular, considering the overlap with adjacent beams not only in the main scanning direction but also in the sub-scanning direction and diagonal direction, in a state closer to the actual machine,
It is possible to measure the scanning beam.

According to the scanning beam measuring method of the eighth aspect of the present invention, in the first step, the light detecting means is moved in the sub-scanning direction in accordance with the deflecting surface irradiated with the scanning beam. By including the steps, it becomes possible to efficiently measure the scanning beam particularly in a state close to the actual machine including the influence of the intensity distribution of the adjacent beams in the sub-scanning direction and the oblique direction. According to the scanning beam measuring method of claim 9 of the present invention, the scanning beam by the continuous first and second deflecting surfaces acquired in the first step is scanned by the scanning beam by the first deflecting surface. Is completed and the detected beam detection information is completely transferred to the storage holding means, and a third step of controlling the exposure timing so that the scanning beam scanned by the second deflecting surface is detected is included. By doing so, it becomes possible to measure the scanning beam in a state similar to that of an actual machine, particularly at a relatively low cost. According to the scanning beam measuring method of claim 10 of the present invention, the scanning beam by the continuous first and second deflection surfaces detected in the first step is scanned by the first deflection surface. After the completion and the positioning in the sub-scanning direction, the third step of controlling the modulation timing of the light source of the scanning beam so that the scanning beam scanned by the second deflecting surface is detected. By including it, it becomes possible to measure the scanning beam particularly in a state similar to that of an actual machine at a relatively low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a main part of a scanning beam measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the scanning beam measuring device in FIG.

FIG. 3 is a schematic diagram for explaining the operation of the scanning beam measuring apparatus of FIG.

FIG. 4 is a schematic diagram for explaining the operation in the case of only one scanning of the scanning beam measuring apparatus of FIG.

5A and 5B are schematic diagrams for explaining the operation in the case where adjacent beams in the sub-scanning direction are taken into consideration in the scanning beam measuring apparatus of FIG.

FIG. 6 is a block diagram showing in detail the configuration of part of the scanning beam measurement apparatus of FIG.

FIG. 7 is a block diagram showing a configuration of a main part of a scanning beam measuring apparatus according to a second embodiment of the present invention.

FIG. 8 is a schematic diagram of a beam spot pattern for explaining a scanning beam measuring device according to a third embodiment of the invention.

FIG. 9 is a timing chart for explaining the operation of the scanning beam measurement apparatus according to the third embodiment of the present invention related to FIG.

FIG. 10 is a timing chart for explaining the operation of the scanning beam measurement device according to the fourth embodiment of the present invention.

FIG. 11 is a timing chart for explaining the operation of the scanning beam measurement device according to the fifth embodiment of the present invention.

FIG. 12 is a flowchart for explaining a scanning beam measuring method according to an eighth embodiment of the present invention.

FIG. 13 is a flowchart for explaining a scanning beam measuring method according to a ninth embodiment of the present invention.

FIG. 14 is a flowchart for explaining a scanning beam measuring method according to the tenth embodiment of the present invention.

[Explanation of symbols]

1 LD (laser diode) section 2 scanning beams 3 rotating polygon mirror 4 lens group 5 PD for synchronous detection (photodetector) 6 Two-dimensional area type CCD (charge coupled device) camera 10 writing unit 13 Host PC (personal computer) 14 Image calculation unit 15 stage controller 16 LD (laser diode) controller 17 Timing control unit 18 programmable counter 19 CCD (charge coupled device) exposure controller 20 memory 21 Main scanning direction stage 22 Sub-scanning direction stage 25 Image synthesizer

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F065 AA03 AA06 DD04 DD06 FF04                       FF49 GG07 HH04 HH18 JJ03                       JJ18 JJ26 LL13 LL14 MM14                       QQ08 QQ24 QQ31                 2G065 AA11 AB09 AB16 BA04 BB49                       BC04 BC11 BC35 CA27 DA05                 2G086 GG03                 2H045 BA33 CA01 CA81 CA88 CA98                       CB01 DA46

Claims (10)

[Claims] 1. A scanning beam measuring device for measuring a scanning beam in a scanning optical system of an image forming apparatus having a scanning optical system for deflecting and scanning a light beam by a rotary polygon mirror, wherein a two-dimensional detection area is provided. Light detection means for detecting the scanning beam to obtain beam detection information, exposure timing control means for controlling exposure timing of the light detection means, and synchronization signal for detecting synchronization information of the scanning beam A synchronization detecting unit for generating a synchronization signal, a counting unit for counting the synchronization signal of the synchronization detecting unit, a synchronization signal generating unit for generating a synchronization signal according to a count value of the counting unit, and a light source for the scanning beam. A light source modulation means for turning on / off a beam, and a beam detection of the scanning beam scanned by a plurality of adjacent deflection surfaces of the rotary polygon mirror. Beam shape based on the information, the position, and the scanning beam measuring apparatus characterized by comprising a calculating means for calculating a beam measurement information including at least one of the beam distance. 2. Storage holding means for storing and holding beam detection information based on light information detected by the light detection means, and image synthesizing means for synthesizing the image of the plurality of beam detection information stored in the storage holding means. In addition to the above, the image synthesizing means includes means for synthesizing beam detection information of scanning beams by a plurality of continuous deflection surfaces of the rotary polygonal mirror stored in the storage holding means, and the computing means includes A means for calculating beam measurement information including at least one of a beam shape, a position, and an inter-beam distance of the scanning beam based on the combined image information obtained by the image combining means. Item 2. The scanning beam measurement device according to item 1. 3. A rotation control means for controlling movement of the light detection means in a sub-scanning direction within a scanning region of the scanning beam, wherein the movement control means is the rotary polygon mirror irradiated with the scanning beam. Of the light detecting means, the exposure timing controlling means includes means for relatively controlling the positioning of the light detecting means in the sub-scanning direction according to the deflecting surface of the light detecting means. 2. The scanning beam measuring apparatus according to claim 1, further comprising means for continuing to expose. 4. The exposure timing control means, when the scanning beam by the continuous first and second deflection surfaces detected by the light detection means ends the scanning of the scanning beam by the first deflection surface, A means for controlling the exposure timing of the light detecting means so that scanning detection of the scanning beam scanned by the second deflecting surface is carried out after the transfer of the detected light information to the storage holding means is completed. The scanning beam measuring device according to claim 2, wherein 5. The light source modulation means is configured such that the scanning beam by the continuous first and second deflection surfaces detected by the light detection means ends scanning of the scanning beam by the first deflection surface and After the positioning in the scanning direction is completed, scanning detection of the scanning beam scanned by the second deflecting surface is performed,
4. The scanning beam measuring device according to claim 3, further comprising means for modulating the light source. 6. The method according to claim 1, further comprising means for moving the light detecting means also in the main scanning direction, wherein beam measurement is sequentially performed in the entire scanning area of the image forming apparatus. The scanning beam measuring device according to any one of 1. 7. A scanning beam measuring method for measuring a scanning beam in a scanning optical system of an image forming apparatus having a scanning optical system for deflecting and scanning a light beam by a rotating polygonal mirror. A first step of detecting a scanning beam by a plurality of continuous deflecting surfaces by a light detecting means to obtain beam detection information, and the scanning based on the plurality of beam detection information acquired in the first step. A second step of calculating beam measurement information including at least one of a beam shape, a position, and an inter-beam distance, the scanning beam measuring method. 8. The method according to claim 7, wherein the first step includes a step of moving the photodetector in the sub-scanning direction in accordance with a deflecting surface irradiated with the scanning beam. Scanning beam measurement method. 9. The beam detection information detected by the continuous scanning beam of the first and second deflecting surfaces obtained in the first step after scanning of the scanning beam by the first deflecting surface is completed. 8. The method according to claim 7, further comprising a third step of controlling the exposure timing so that the scanning beam scanned by the second deflecting surface is detected after the transfer of the data to the storage holding means is completed. Scanning beam measurement method. 10. The scanning beam by the continuous first and second deflecting surfaces detected in the first step is the first beam.
Modulation timing of the light source of the scanning beam so that the scanning beam scanned by the second deflecting surface is detected after the scanning of the beam by the deflecting surface is completed and the positioning in the sub-scanning direction is completed. 9. The scanning beam measuring method according to claim 8, further comprising a third step of controlling.